Cesar Azpilicueta confronted a fan after Chelsea's 4-2 loss to Arsenal and Thomas Tuchel understood why the supporter was angry.
Chelsea suffered their third straight home defeat in all competitions on Wednesday and the Chelsea captain approached an individual in the stands after the final whistle.
Timo Werner and Azpilicueta cancelled out first-half strikes from Eddie Nketiah and Emile Smith Rowe, but the Blues went on to suffer a bitter defeat.
Azpilicueta's stray pass preceded Nketiah scoring a second, while he gave away a penalty that Bukayo Saka converted in stoppage time to leave Chelsea just five points clear of the fifth-placed Gunners.
The Blues have now lost three straight home games in all competitions for the first time since November 1993, while December 1989 was when they previously conceded at least four goals in successive home league matches.
Still, Azpilicueta was seemingly angered by the response of the fans and approached a group of spectators, with one appearing to hold their hands up in apology.
Asked about the incident, Tuchel said: "I saw it. Honestly, I can understand the fan.
"It was a totally wild and open game in the first half – already a 2-2 after we came back twice. We had a good start but again gave the first goal away which is impossible to do these things in consecutive matches. But we're doing it.
"We came back twice and we scored another two in the second half, unfortunately for the wrong side.
"It's the level of mistakes, the number of mistakes in consecutive games here at home, it's impossible at this kind of level. You don't see this. It's simply impossible. But we're doing this at the moment and you cannot win football games like this.
"To say the pitch is difficult to play here, it maybe sounds like an excuse, but it is a very, very difficult pitch that we have here. It’s not in our favour.
"The ball bounces very awkwardly in front of Andreas [Christensen] when he wants to play this ball. But still, we had the same mistake against Real Madrid that cost us the next round of the Champions League and this one cost us the next match. I can't remember when we got two goals like this
"Look at the penalty, it is an unbelievable goal from our ball possession. There are no tactics behind that. We have three ball losses in 10 seconds. Then we do a foul where there's not even the slightest danger. We foul a person, it is a penalty and we rob ourselves six minutes for an equaliser.
"It must be something, but it is also possible to not do it because we proved it in the last three matches and we thought we learned our lesson from Brentford and Real Madrid, but obviously not."