Jurgen Klopp say Liverpool would have held on for a win against Chelsea on Saturday had he been able to make a late substitution before Willian's late equaliser.
Mohamed Salah had broken the deadlock in the 65th minute at Anfield, and with the game winding down, Klopp had Adam Lallana ready to replace Philippe Coutinho.
But despite being ready to make the change, referee Michael Oliver chose to wave play on, and Chelsea levelled soon after.
Speaking at the end of the game, Klopp said: "Maybe ask the ref. I don't know. People can say we are not really smart, but if you want to change the system and bring on a player you need to give advice.
"I wasn't happy about it because we wanted to change. In my mind, Ragnar Klavan would have been exactly in the position where Willian would have crossed the ball, so we would have blocked the cross.
"So that doesn't feel too good because we couldn't change the system because the ref thought maybe let's time play or something else, I have no idea why he said no, go and play.
"My assistant was prepared, I was prepared, the player was prepared, but the ref said go on play, and it was around four minutes. That's what he said to me after the game, 'the goal was four minutes after you wanted to change'. That didn't make me feel much better."
In reflection, the German mentor was pleased with the performance of his side.
"It was a good game, very intense game," Klopp added. "Very difficult for us against a very strong Chelsea team with quite a different approach.
"I am happy about big parts of the performance and really proud of the attitude. Everything was good until Willian crossed the ball, still most parts of the game were good but it doesn't feel as good."