Jurgen Klopp was unhappy with the refereeing in Liverpool's 2-0 loss to Napoli in the Champions League on Tuesday night.
The game looked destined from a draw until Andy Robertson fouled Jose Callejon in the box after 81 minutes.
Replays showed Callejon initiated the contact to Robertson's outstretched leg, but nonetheless, Lorenzo Insigne stepped dutifully to fire home Napoli's first of the game.
An uncharacteristic error from Virgil van Dijk then allowed Fernando Llorente to score his first goal for Napoli to double their advantage.
Speaking after the game, Klopp was adamant Robertson should not have been penalised for the challenge with Callejon.
He told BT Sport: "It should hurt because there were opportunities for us. It was an open game with a lot of counter attacks, but we didn't finish them off and that is a problem.
"In the second half it was a wild game, they were running and we were running.
"I don't think it's a penalty. What can I say, for me, it is clear and obvious no penalty. He jumps before any contact, we can't change that.
"We played a lot of good football but didn't finish it off. We controlled moments but had not enough chances in the end. We made decisions that were not right and have to accept the result. It was very often the final ball that was not right."
Napoli defeated Liverpool 1-0 at the San Paolo Stadium in the Champions League group stages last season.
