After Ajax - PSV, Pol van Boekel is also under fire in the Champions League

Controversy flared in the second half of FC Porto v Manchester City (0-2). Marc Guéhi caught Gabri Veiga in the face with an elbow, but the incident went unpunished and drew criticism of VAR Pol van Boekel.

During a duel, the Manchester City defender hit the FC Porto player in the face with his arm. Referee Szymon Marciniak took no action, and Van Boekel did not send him to the pitchside monitor to review the incident.

Shaken by the collision, Veiga had to go off for treatment. The Spanish midfielder, in Portuguese service, did not need to be substituted, however.

On the touchline, Porto coach Francesco Farioli threw his hands in the air as he waited for Guéhi to be punished by the officials. Home players and supporters were furious too.

Van Boekel also came in for criticism last weekend. Working as VAR, he did not call referee Sander van der Eijk over to the monitor after Ruben van Bommel's challenge on Aaron Bouwman.

Mike Verweij of De Telegraaf reported on Monday that Van Boekel is heading towards retirement. "I think the intention is for him to stop in December or January. There is some discussion about whether they should continue with him or not. But then you must not make too many decisions of this kind, or rather forget to make them," it was said on Kick-Off.