Graham Potter had no complaints about Joao Felix's red card as he bemoaned losing another player.
The Blues boss saw his side lose for the third time in a week as they were downed by local rivals Fulham, who are now six points clear of Chelsea. Vinicius headed home the winner for the Cottagers, but only after the visitors went down to ten men.
Felix was signed on loan this week from Atletico Madrid and went straight into the starting XI. Chelsea have struggled for goals and the Portuguese forward will help them in the final third, but his impact will now be delayed as he was sent-off for a second-half lunge.
It means the new arrival will face some time out through suspension, but Potter found it hard to complain with the decision after a reckless challenge on Kenny Tete. Potter told BT Sport: "It was a forward's tackle, there was no malice in it but I understand why it was a red. It is another blow the hits keep coming at the moment. He was really good you could see his quality in the game, so it is doubly disappointing for us."
Chelsea's poor run of form has seen them win just once in nine league games either side of the World Cup break. Pressure is mounting on the former Brighton boss, who only took over from Thomas Tuchel back in September. Their loss means they failed to close in on the top four and attention will now turn to the weekend's clash with Crystal Palace.
Potter bemoaned their defending for the winning goal at Craven Cottage, after Kalidou Koulibaly had got the Blues back level. Vinicius was afforded a free header at the back post and the Chelsea boss felt more could've been done.
He added: "I think we controlled the game early won the ball back high created some opportunities maybe missed the last pass. We made a couple of mistakes for their goal. Second-half I think we responded well and then the red card changes the game.
"Makes it a little more difficult for us, I thought the application when we went down to 10 was really good. Disappointed with the goal because I think we could do better and that is what cost us. We have got to keep working there is no other solutions, you have to keep working stay together and try to get the three points."
Former Blue Willian, who scored the opener, said on his side's win: "We deserved the win. We know how difficult it is to play against Chelsea. They are in a difficult moment but we are a really good team. We deserved it and we have to carry on.
