Liverpool cruised to victory in the first leg of their Champions League quarter-final tie with Porto. Goals from Naby Keita and Roberto Firmino handed the Reds an important home win and they now go to Portugal with a comfortable lead to protect. Jurgen Klopp's side could have scored even more too - they were so dominant over the 90 minutes. Although it was a faultless Liverpool performance with two goals and a clean sheet, they did get away with one big moment and it involved Mohamed Salah. With five minutes left, the Egyptian forward was chasing the ball on the edge of the box and appeared to stamp down on the leg of Porto's Danilo Pereira when he came across to clear the ball.

Salah's challenge was very late and very high - one that clearly warranted punishment. But incredibly, he escaped without a card. He wasn't even booked, let alone sent off. 

You can watch the incident below. 

It seems unbelievable that the Liverpool forward didn't even get booked for an awful, over the ball challenge. 

He was perhaps helped by the fact that Pereira seems to have downplayed the challenge. 

Of course, it's unclear if there was any intent on Salah's part - yet it seems he could have easily avoided stamping down on his opponent's leg. 

It's also a shame that this incident could overshadow Liverpool's impressive first leg win. 

It took them just four minutes to open the scoring when Keita's shot from outside the box was deflected past Iker Casillas and into the net. 

Firmino doubled his side's lead, tapping home from close range after Trent Alexander-Arnold sent a low cross into the six-yard box. 

Liverpool are in a strong position thanks to the result and will be confident of finishing the job next week. But they were rather lucky to finish the game with all 11 players on the pitch.