Punjab, who finished the season in top spot with a record of 11 wins and three losses, won the toss and chose to bowl first this afternoon in Kolkata.
By that time he had put on a 65-run partnership with Manish Pandey (21) and the rest of Kolkata's middle order all contributed scores around the 20 mark as they finished their 20 overs on 163-8.
Patel was the star bowler for the Kings XI, finishing with two wickets and just 11 runs scored off his four overs.
However, unlike the Knight Riders, Punjab couldn't find decent scores in the middle and eventually fell 28 runs short on 135-8.
Umesh Yadav was the pick of Kolkata's bowlers, taking three wickets and conceding just 13 runs in his four overs.
They still have a chance to reach the final, though, as they will now go on to face the winner of the eliminator later today between the Chennai Super Kings and Mumbai Indians on Friday.
The winner of Friday's qualifier will then go through to face Kolkata in Sunday's final.