Chelsea boss Enzo Maresca expressed his concern that referee Jarred Gillett did not agree with him that Will Hughes' foul on Cole Palmer warranted a second yellow card, which could have turned the momentum back in the Blues' favour during their 1-1 draw at Stamford Bridge with Crystal Palace.
The 29-year-old Eagles midfielder had already been booked for pulling back Nicolas Jackson, who had fired the hosts into the lead after 25 minutes.
But just moments into the second half, Palmer was though on goal and in a promising situation to extend Chelsea's lead, only to be pulled back again by the same culprit.
Maresca fumed on the touchline and Hughes was swiftly taken off by Oliver Glasner, but just a few moments later Eberechi Eze equalised and Chelsea dropped two points.
“It was clear to all of us it was a second yellow card," Maresca explained in his post-match press conference. "The only one who thought otherwise was the referee. We were 1-0 up. It completely changed. The reaction from their bench was quite clear. But the fourth official told me the referee did not consider it a yellow card.
"This kind of thing for sure changes the game. It was (a) clear second yellow card but the referee thinks in different ways. We completely deserved to win the game. We controlled the game. The performance was very good."
Maresca also admitted that he was "concerned" over the Chelsea defence and their inability to keep clean sheets this season, while confirming a potentially crucial injury blow.
"First of all, I am always concerned," he explained. "It doesn't matter whether it's a clean sheet or not. We conceded a goal but we didn't concede any more chances."
When asked why right-back Malo Gusto was substituted off, he added: "Looks like a muscle problem. We will see."
Maresca was buoyed with some off-the-pitch decisions, however, following the addition of Jadon Sancho on an initial season-long loan and plans to extend Jackson's contract.
"Jadon is a player, he is here because we like that kind of player - especially against a low block like today," Maresca explained. "With these kind of games, we have five, six or seven chances here. There are not many teams that can do something to win the game."
On reports that Jackson would extend his stay at Stamford Bridge after the Blues failed in their deadline-day attempts to sign Victor Osimhen, the head coach said: "The only thing I know is he's signing a new contract - I don't know how many years. I'm very happy. Nicolas is doing a fantastic job with us. He scored again. He had more chances but we're happy with him."