She was 4-0 down in the first set in 10 minutes but, despite getting one of the two breaks back she went down 6-4.
However, she battled back to take important breaks in the second and third sets, finally wrapping the match up on Pironkova's serve.
Read how the action unfolded below.
2.48pmHello everyone and thanks for returning for our court two coverage. Up next we have a very interesting clash between the fourth seed Radwanska and Pironkova.
2.51pmIn the head-to-heads, Radwanska is well on top. She has seven wins to the Bulgarian's one.
2.54pmHowever, Pironkova has been very good at times this year, and is a semi-finalist from 2010. The warmups are about done already and Radwanska will serve first.
2.56pmShe's finding her accuracy early on, but Pironkova is right in it. She spots Radwanska well behind the baseline and plays a nice drop shot into the space.
Radwanska 0-1* PironkovaBREAK! What a start for the Bulgarian! She works a point nicely at advantage to slap a winner across court and take the break at the first time of asking. Could there be an upset on the cards here?
Radwanska *0-2 PironkovaNo problems on her own serve either for Pironkova, who holds relatively comfortably to consolidate the break. How can the world number four respond to this?
3.02pmIt doesn't seem like she can as she finds the net with a volley, but then gets a reprieve as Pironkova goes long with an easy forehand.
3.02pmWhat a pass from Pironkova! The Pole moves to the net but is beaten with a backhand right down the line for 30-30.
3.03pmPoor unforced error from a backhand by Radwanska and Pironkova has a break point...
Radwanska *0-3 PironkovaBREAK! What a start for the Bulgarian! Both women come into the net but it's the world number 72, as Radwanska goes wide with a difficult lob. The fourth seed needs to wake up here.
3.08pmPironkova is controlling the rallies. Radwanska isn't sure whether to go to the forehand or backhand of her opponent - both look lethal at the moment and she's 40-15 up.
3.10pmMuch, much better from Radwanska. She swats away a forehand as much out of annoyance as anything for 30-15. However, a great return sets up a net point for the Bulgarian to get one back.
Radwanska 1-4* PironkovaShe's finally on the board here and it took a while coming. Pironkova played two really good points, but the Pole did well to quell her efforts there. Still two break behind, though.
3.12pmHuge roars can be heard from Centre Court, and that's because Sabine Lisicki has taken three breaks in a row to move 5-4 ahead in a deciding set against Serena Williams. Surely not? Find out....
3.14pmRadwanska does really well to chase down a drop shot and force her opponent to net. She has a look-in here, at 0-30...
Radwanska *2-4 PironkovaBREAK! She takes it with her second chance, setting up a point brilliantly to slam the winner at the net. That's one of two breaks back. This is getting good.
3.18pmIt's 15-15 here, but there's another HUGE upset today. Lisicki has knocked out Serena!
Radwanska 3-4* PironkovaRadwanska takes her third game in a row, and with a break here would pull level. It's all going wrong for Pironkova at the moment and really needs to hold now.
3.22pmVery good response from Pironkova, who goes 30-0 up after controlling two points neatly.
3.23pmHowever, after drawing Radwanska to the net with a drop shot her lob is way out.
Radwanska *3-5 PironkovaPironkova nets a backhand and the Pole is back in this game - however, she then puts a return wide and Pironkova makes no mistake afterwards to slam a backhand down the line.
3.27pmSET POINT Pironkova! A really good rally ends with Radwanska netting...
3.27pmShe tightened up at just the wrong moment! Radwanska was out of the point and Pironkova goes long with a forehand for deuce.
3.28pmThen a brilliant drop volley from Radwanska catches her opponent off guard for advtantage.
3.28pmGreat strike from Pironkova on the forehand, who beats the Pole for sheer pace across court.
3.29pmOn game point again it's a double fault from Radwanska - her second - to take us to deuce for the third time. Now set point as Radwanska puts a backhand into the tramlines.
Radwanska 4-5* PironkovaThere's that dodgy bit of court again as Pironkova slips. She's ok, but lost her advantage and Radwanska follows it up with advantage of her own and then a volley for the game. So the Bulgarian has to serve this one out, then.
3.34pmShe has one of the better serves in the women's game, Pironkova but perhaps not her second - the leaves one ripe for dispatch, however Radwanska skews it at the umpire. Now three set points for the Bulgarian...
3.35pmThe first is saved nicely with some aggressive tennis, ending with a Radwanska smash.
Radwanska 4-6 *0-0 PironkovaSET! She keeps her bottle and Pironkova takes the first set. She's deserved that, too, as her serve was far more impressive throughout.
3.40pmThe umpire hasn't noticed that the players have come out after the break to the same end they were at before. It's suiting Radwanska, as she goes 40-0 up.
3.43pmPirinkova's 10th unforced error puts her in a bit of trouble at 0-30, and then Radwanska earns two break points with a nice volley...
3.45pmReally good tennis from Pironkova, as she's worked left, right and then to the net before winning the point with an overhead volley. Classy stuff, and that's pulled it back to deuce, too.
Radwanska 4-6 *2-0 PironkovaBREAK! Another break point Radwanska, and this time she takes it with a forehand hit right at the feet of Pironkova, who cannot adjust.
3.48pmRadwanska has no option but to try the flick between her legs from a lob, but hits it narrowly out - great attempt.
3.49pmPironkova brings it to deuce with a brilliant backhand down the line.
Radwanska 4-6 3-0* PironkovaIt was tough going for Radwanska, but a hold is a hold. Nothing looks to be giving in the longest rally of the match, until the Pole puts a touch more power on a forehand that forces her opponent to net. This set has gone the opposite way of the first.
3.53pmGreat drop shot from Pironkova to start the next game. It's really well disguised from the baseline and Radwanska quickly gives up the chase. It's followed with an emphatic smash at the net - I think she took out a bit of her frustration there.
3.54pmFantastic response from Radwanska, who takes the point into her own hands to hit a backhand winner across court after a few Pironkova slices.
3.55pmBOOM! What a backhand from Pironkova. She waits for it to bounce on the baseline and thrashes it down the line for the winner.
Radwanska 4-6 *3-1 PironkovaA really well worked point finishes the game. She showed a lot more of her first set ability there, and that should encourage her.
3.57pmAt 30-15 Pironkova gets a bit of luck with a shot clipping the top of the net and dying. Can she get the break back? There's certainly a chance, as Radwanska's fourth double gives her break point...
3.58pmRadwanska comes to the net to save it. Pironkova tries to go through her, but it's well controlled by the fourth seed.
3.59pmReally good overhead from Pironkova, who saves game point with a smash as she was walking backwards.
Radwanska 4-6 4-1* PironkovaIn the end Radwanska manages the hold and the odds very much are on that this will go into a deciding set. I hope so, as it's been gripping thus far.
4.03pmBack to court two, and Pironkova has just netted at 30-0 up. She was looking good to that point.
4.04pmGood defensive work from Radwanska, who finds an angle with her forehand and Pironkova puts hers into the net.
4.05pmA well worked point from Radwanska at 40-30 down and she hits the winner down the middle coming into the net. Deuce.
4.06pmPoor from Pironkova. She nets right at the net trying to return a Radwanska drop shot and now there's a break point for the Pole...
4.07pmPironkova saves it with an ace, then gets advantage with a terrific backhand down the line - that's a few times she's pulled that one off now.
4.08pmThis time her overhead smash is well, well wide for deuce number three, but she follows it up with an aggressive point and a forehand winner.
Radwanska 4-6 *4-2 PironkovaA good, and important, hold for Pironkova. Radwanska cannons a return wide and the Bulgarian stays alive in the set.
4.11pmIt's 30-15 here for Radwanska. If she holds, you feel that's the set all-but wrapped up. However, Pironkova reads a drop shot really well to steer the winner down the line for 30-30.
Radwanska 4-6 5-2* PironkovaShe holds with a big serve, which clips the edge of Pironkova's racquet and hits a man in the crowd on the arm. He rubs his elbow, but come on, it's a tennis ball.
4.14pmVery good shot to open the game from Pironkova. She waits for a Radwanska shot to bounce before steering the forehand down the line.
Radwanska 4-6 *5-3 PironkovaA 104mph ace brings up game point and she finishes it with another powerful shot right at the net. It was an important hold to get a bit of momentum up ahead of trying to break. Radwanska to serve for the set.
4.16pmThe Bulgarian is 0-30 up here. This is her chance.
4.17pmThat was a good chance with a backhand to set up some break points, but goes long and wide instead and then a point later Radwanska wins at the net for 30-30.
Radwanska 4-6 6-3 0-0* PironkovaSET! That's how you want to serve for a set! An ace out wide finishes it and we're into a decider. Pironkova has a problem with her foot and has called for the trainer - he or she has a long way to come, so there will be a short break.
4.24pmThe trainer is here and is currently 'evaluating' the Bulgarian's foot. There are a lot of questions and nodding going on. I'm not being funny, but her feet are pretty big!
4.26pmEvaluation phase is over, so the trainer now has three minutes to make Pironkova's toe all better.
4.39pmBreak point for Radwanska, but Pironkova saves it really well with a drop shot.
4.40pmWow. What a shot from Pironkova. She takes it on the bounce from the baseline and powers a forehand winner into the opposite corner.
Radwanska 4-6 6-3 *2-1 PironkovaBREAK! A probably decisive break for Radwanska there, who wins with a lob that Pironkova throws her racquet at - but in vain. The trainer is back. That's got to be the nasty part of her job, working on feet.
4.45pmThat's a lazy drop shot from Pironkova at 15-30 down. It bounces nicely at shoulder height for the Pole to hit the winner, but the Bulgarian then responds with a fine cross-court pass.
Radwanska 4-6 6-3 3-1* PironkovaIt's too good from Radwanska, who runs Pironkova all over the court before hitting the forehand winner to consolidate the break. I can't see the Bulgarian getting back into this now.
4.47pmBrilliant shot! Again it's the backhand from Pironkova, which is by far her best shot. It clips the line and puts her 30-0 up, but then a sloppy shot afterwards goes into the net.
4.49pmIt's another quite poor drop shot from Pironkova, but not nearly as bad as the forehand to follow it that was barely halfway up the net.
Radwanska 4-6 6-3 *3-2 PironkovaThere was good and bad from the Bulgarian in that game, but it was a comfortable enough hold in the end. Can she now get a look at the Radwanska serve?
4.54pmPironkova is still trying hard, and she saves game point to bring deuce with another fiery backhand. This one isn't a winner, but there's too much on it for the Pole to return.
4.57pmThat is just a ridiculous drop shot from Pironkova. It's advantage to the Pole and the Bulgarian gets it to spin away from her as she rushed towards it.
Radwanska 4-6 6-3 *4-3 PironkovaThat backhand is really ferocious from the Bulgarian as she swipes one cross-court from above her head. Radwanska responds with a brilliant forehand return but Pironkova wraps up the game at the net after a really fine rally from both women.
5.04pmA wail from Pironkova, who skews a forehand well long for 40-0.
5.09pmIt's a break at the perfect time for Radwanska, who was just too strong in the end after a slow start. She moves on to face Li Na of China for a spot in the semis.
5.11pmThanks for joining me today for the court two action. There's plenty still going on including Andy Murray's battle against Youzhny on Centre. You can follow that with us, but from me it's goodbye!