Tottenham Hotspur head coach Mauricio Pochettino said he was "unhappy" to see his side beat Chelsea 1-0 in the first leg of their English League Cup semi-final via a disputed penalty awarded by VAR.
Harry Kane scored the only goal of the all-London tie at Wembley after 26 minutes with a spot-kick given when referee Michael Oliver called on video technology.
Chelsea were convinced Kane had been offside before racing into the box, where he was brought down by Kepa Arrizabalaga as the Blues goalkeeper came hurtling off his line.
It took more than 90 seconds for VAR to confirm Kane had indeed been onside before match referee Oliver awarded a penalty.
"I don't like the VAR," Pochettino told Sky Sports. "Today we get the benefit of it but after watching the World Cup and another league like La Liga I see that nobody is happy from day one that they started to use it."
"To get the benefit is nice but I am unhappy to win the game like this," the Argentinian added.
"I prefer the technology but in a different way. Being clear, I am pro technology because you cannot stop evolution but we are waiting so long, it is not clear what are the rules.
"We all have to agree, the players, the coaching staff, I watch every week La Liga and nobody is happy, the big clubs and the small clubs.
"That is a good example for us. We have six months to improve the system and there is a lot of work to do."
Meanwhile, Chelsea boss Maurizio Sarri insisted a Blues video showed Kane in an offside position and also questioned why VAR was now being used in League Cup ties but not in the Premier League.
"A few minutes ago I watched the video from our camera. It was offside. Our camera was in line with Harry Kane," Sarri said.
"Offside with the head, the knee. Offside. It was really important the linesman carried on running, he had a big impact on our defenders.
"I don't think English referees are able to use the system. If you are not sure with the system, you have to follow the ball and at the end of the action decide...
"I think they (football officials) have to study the system. It's very strange in the Premier League there isn't VAR and in the Carabao (League) Cup there is the system. It's very strange for us, the players and referees."
Kane, however, had no such qualms over the penalty award.
"I played to the whistle and nicked it round the keeper, it was a clear penalty. VAR is there for a reason and they got it right," said the England forward.