Hello and welcome to Sports Mole's live coverage of the second leg of the Champions League quarter-final between Porto and Liverpool. The Premier League giants hold a two-goal advantage after the first leg at Anfield, but Porto have been excellent at their home ground in this season's competition. The two teams are making their way out onto the pitch in Portugal, so let's see who features in each starting lineup...

PORTO XI: Casillas; Felipe, Pepe, Militao, Telles; Herrera, Danilo, Otavio; Corona, Marega, Brahimi

PORTO SUBSTITUTES: Vana, M.Pereira, Costa, Torres, A.Pereira, Soares, Andrade

LIVERPOOL XI: Alisson; Alexander-Arnold, Matip, Van Dijk, Robertson; Milner, Fabinho, Wijnaldum; Salah, Origi, Mane

LIVERPOOL SUBSTITUTES: Mignolet, Gomez, Henderson, Keita, Shaqiri, Firmino, Sturridge

Porto get us underway!

SHOT!  The home side nearly go in front after just 32 seconds! Corona cuts inside onto his left foot and sends a fizzing effort marginally over the far top corner.

Liverpool have had a couple of attacks since that near miss, but it was a reminder that they cannot afford to take Porto lightly this evening. It is also worth noting that there has been a spell of heavy rain before kickoff. The ball is zipping off the pitch.

LATEST! We are also providing coverage of the game between Manchester City and Tottenham Hotspur, and the home side have already taken the lead at the Etihad Stadium! It's now 1-1 on aggregate. Click here to follow that contest.

Back to this game, and Porto are certainly pushing for an early goal in Portugal. Liverpool are not always looking confident at the back, either.

Spurs have got themselves level in the other match.

LATEST! Shall we just provide you updates of the other match instead? Spurs now lead at the Etihad Stadium and Man City already need to score at least four on the night!

Porto win a corner which is swung in viciously from the left. However, Pepe fails to make a proper connection and the ball go out on the far side of the pitch.

Man City are now level with Spurs. It's 2-2 after just 11 minutes. Absolute madness!

A ball from the left finds Salah in space on the opposite side of the pitch. It's a similar area to where the Egyptian netted his wonder goal against Chelsea, but the winger cannot get a shot away on this occasion.

A cross from the left finds Marega around 12 yards out, but the forward seems surprised to receive the ball! It bounces off his head and goes harmlessly wide for a goal kick.

CHANCE!  Marega certainly expects the ball this time. The forward decides to send a first-time volley towards goal, but the ball goes a yard or two wide of Alisson's right-hand post.

Liverpool really don't look comfortable. If they concede one, you fear for them. Klopp has rejigged his attack with Origi now playing down the centre, but all his focus should be on the defence.

Alexander-Arnold wins a free kick for Liverpool in the middle of the pitch, and it gives the visitors a chance to take a breather. It's been a fast-paced start, but all of the running has been made by Porto.

LATEST! Man City now lead by a 3-2 scoreline at the Etihad Stadium! Sterling has netted his second. Remember that you can keep up-to-date with our coverage by clicking here.

The last few minutes have been more stop-start but again, that suits Liverpool. Nevertheless, Porto continue to plough forward when they have the opportunity.

It has been a while since Liverpool were required with their backs against the wall. Matip has made a block and miscued a clearance over the past couple of minutes.

Big chance for Porto. Corona finds himself through on goal with just Allison to beat, but the winger wants far too much time and it allows Van Dijk to get back in order to make an important challenge.

GOAL!  PORTO 0-1 LIVERPOOL (SADIO MANE)

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GOAL!  Liverpool take the lead and in doing so, may have just wrapped up the tie. Mane's close-range effort after meeting a Salah shot was initially ruled offside, but VAR has ruled that the winger was marginally onside! Porto now need four...

It took a while for that decision to be made - Mane himself appeared to accept that he was offside - but the technology has reached the right call. I suspect that Klopp is an admirer of VAR.

That goal has not quite stopped Porto in their tracks, but they are aware that they must get back on level terms before half time. Liverpool will surely sit a little deeper at least until the break.

The atmosphere isn't quite what it was, either. The Porto supporters understand the situation, and they may also be wary of another heavy defeat to the Merseyside giants after their capitulation last season.

YELLOW CARD!  Pepe goes into the book for clattering into Origi. The Portuguese is only just back from a ban!

Liverpool are doing a better job of keeping the ball away from their own final third. It was necessary because they certainly rode their luck during the opening stages of the game.

SHOT!  Corona has had plenty of success with cutting inside from the left, but the winger again cannot beat Alisson. His shot was on target, but far too close to the Brazilian stopper.

There is a real danger of this game going flat after the break if Porto do not pull a goal back. There is still urgency from the home side, but not enough to cause Liverpool too many problems.

Herrera and Marega attempt to combine just inside the area, but Van Dijk and Robertson do just enough to keep the ball away from goal.

There will be two minutes of added-on time.

HALF TIME:  PORTO 0-1 LIVERPOOL

The half-time whistle goes at the Estadio do Dragao and Liverpool lead thanks to Mane's close-range strike, given through the use of VAR. Porto have been the better side, but the Portuguese giants need a miracle. Liverpool came agonisingly close to a second just before the half-time whistle, but Milner's flick from an Alexander-Arnold cross was deflected just wide of the far post.

Interested in the player statistics from that opening 45 minutes? Don't worry. We have you covered. Click here to read up on both teams.

A quick reminder of both benches...

PORTO SUBSTITUTES: Vana, M.Pereira, Costa, Torres, A.Pereira, Soares, Andrade

LIVERPOOL SUBSTITUTES: Mignolet, Gomez, Henderson, Keita, Shaqiri, Firmino, Sturridge

KICKOFF:  Liverpool get us back underway. Both teams have made a change at the break, with Soares replacing Otavio for Porto and Liverpool introducing Firmino for Origi.

Porto have had plenty of success in the opening stages of the second half, but they are yet to get a shot on goal. It is imperative that they find an equaliser very soon.

More positive play from Corona leads to a cross being floated into the penalty area, but a Liverpool defender manages to divert Marega's header away from goal.

Porto have had a quieter two minutes, but they are still keeping Liverpool on the back foot. Klopp won't be too pleased with what he is seeing.

CHANCE!  A cross is delivered from the right, and the quality of the ball enables Soares to get above Matip. However, the substitute's header is powered wide of Alisson's left-hand post.

It is easy to forget that Liverpool are ahead in this game. They have only really had three attacks in the entire match. It's all about progression though, I guess.

SHOT!  A fourth attack ends with Salah sending a header towards goal, but the Egyptian's effort is never troubling Casillas.

SHOT!  Herrera tries his luck from all of 30 yards, but the midfielder's strike goes straight into the hands of Alisson.

LATEST! Manchester City have moved 4-2 ahead against Spurs. They now have the advantage on aggregate! Click here to follow the closing half-hour at the Etihad Stadium.

It appears that Gomez could be making an appearance for Liverpool very soon. The England international has been missing for several months due to a broken ankle.

We have probably reached that stage where this game is completely beyond Porto. There are signs of both teams beginning to go through the motions.

GOAL!  PORTO 0-2 LIVERPOOL (MOHAMED SALAH)

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GOAL!  Well it is now. Alexander-Arnold threads the perfect through-ball into the path of Salah, leaving the Egyptian to take a touch before slotting the ball under Casillas and inside the near post.

SUBSTITUTION! Klopp follows that up by introducing Gomez for Alexander-Arnold.

GOAL!  PORTO 1-2 LIVERPOOL (EDER MILITAO)

GOAL!  Game on?! No...but Porto get the goal that they deserve. An outswinging corner picks out Militao, who powers a header into the far corner from 10 yards out.

SUBSTITUTION! Klopp makes his third change with Henderson being introduced for Robertson. Milner has moved over to left-back.

CHANCE!  Liverpool should have their third with Mane being released clear of the defence. However, despite taking the ball around Casillas, the winger can only send his shot wide of the target.

LATEST! It has been an outrageous game at the Etihad Stadium. Spurs have got it back to 4-3 and now lead on away goals! Click here to follow the final 15 minutes but added-on time.

GOAL!  PORTO 1-3 LIVERPOOL (ROBERTO FIRMINO)

GOAL!  Liverpool eventually get their third through Firmino. Henderson's cross from the right is perfect for the Brazilian to glance a header into the far corner from 10 yards out.

SUBSTITUTION! Porto make a second alteration with Fernando replacing Corona.

Liverpool have been second best for much of tonight's game, but you have to be impressed with how they have still managed to negotiate this game with minimal alarm.

CHANCE!  Soares should pull another goal back for Porto, but the substitute can only send his poked effort from 15 yards wide of Alisson's right-hand post.

GOAL!  PORTO 1-4 LIVERPOOL (VIRGIL VAN DIJK)

GOAL!  This is ruthless from Liverpool. An inswinging corner is flicked on into the path of Van Dijk, who converts a simple header from no more than six yards out.

Porto look pretty much done here. It would be harsh on the Portuguese side if they concede a fifth, but do not rule it out.

You have to be impressed with how Liverpool have continued to push for goals. They could have slowed everything down from an hour onwards, but Klopp is witnessing his team make a big statement.

There will be just two minutes of added-on time.

FULL TIME:  Porto 1-4 Liverpool

The full-time whistle goes in Portugal and Liverpool have registered a ruthless 4-1 win over Porto. Klopp's side did not have it all their own way, but the Premier League giants have managed to set up a last-four showdown with Barcelona.

That will be all from Sports Mole for this game. Thank you for joining us this evening and we hope to see you again soon.

If you would like to read our on-the-whistle match report, you can do so by clicking here. Goodbye for now.