Joao Felix sent off in Chelsea Fulham loss

Joao Felix has been sent off on his Chelsea debut as his new team lost 2-1 at west London rivals Fulham in the Premier League to fall deeper into crisis.

The Portugal forward was shown a straight red card in the 58th minute for his dangerous studs-up challenge on Kenny Tete that caught the Fulham right-back just below his right knee.

Felix, who joined the Blues on loan from Atletico Madrid for the rest of the season on Wednesday, was having an impressive game until his sending-off, making surging runs, delivering incisive passes and showing some neat touches.

He will not be able to showcase them again until February 11 as he will now miss league games against Crystal Palace, Liverpool and the return fixture with Fulham.

With Felix having joined on a deal costing Chelsea a reported $A1.1 million a week taking in wages and the loan fee, it is a costly error for the club and their under-pressure manager Graham Potter.

"It was a forward's tackle. There was no malice in it but I understand why it was a red," Potter said.

"It is another blow. The hits keep coming at the moment, that's how it is. He (Felix) was really good, you could see his quality in the game, so it is doubly disappointing for us.

"We have got to keep working. There is no other solution, you have to keep working to stay together and stay focused."

Chelsea slipped to a sixth loss in their last eight matches in all competitions - their worst run of results in nearly 30 years - thanks to a 73rd-minute winner from Carlos Vinicius.

The Brazilian striker was only playing because first-choice centre forward Aleksandar Mitrovic was suspended.

Fulham went ahead in the 25th minute through a deflected shot from former Chelsea winger Willian, only to concede an equaliser shortly after halftime when Mason Mount's free kick came back off the post and Kalidou Koulibaly forced home the rebound.

The result takes Fulham above Liverpool into sixth place to continue a brilliant first season back in the top flight, while Chelsea remain a disappointing 10th.

"It is a consequence of everything we are doing," Fulham defender Tim Ream said.

"The hard work on the training ground, the togetherness of the players and fans. We are not looking at the table but we are in a very good position."