Slaven Bilic felt Diego Costa should have received a second yellow card prior to scoring Chelsea's winning goal against West Ham, but was more upset with his side conceding so late in the game.
Costa's dramatic long-range strike with one minute remaining on Monday gave Antonio Conte a 2-1 victory in his first competitive game in charge of Chelsea, but the striker was fortunate to still be on the pitch.
Having received an early yellow card for dissent, Costa avoided a second booking from referee Anthony Taylor for a 67th-minute lunge on West Ham goalkeeper Adrian, which was given as a foul without further punishment.
Bilic acknowledged that Costa would normally have seen red, but was more frustrated by his side's failure to hold on for a point after James Collins had cancelled out Eden Hazard's penalty.
"Diego Costa had already been booked," the West Ham boss said at his post-match media conference.
"It was late - very late - and nine times out of 10 when you see that challenge on a goalkeeper, it ends up with a booking.
"Unfortunately this was the 10th time, but I'm more interested in talking about the game than Diego Costa.
"From my point of view I've seen the incident again and I don't think Costa was reckless. It was not a reckless or deliberate one but it was quite late, the ball had gone. He could have been booked again and so a red card.
"But I am not frustrated because of that, I am frustrated because of the late goal. When you lose a game and concede late, of course you are disappointed.
"We came back into the game, we played well after 1-1 but we made the mistake in the middle of the park. We gave the ball away and conceded a cheap goal."