Potter cannot seem to catch a breather at the moment as another misfortune befell his side shortly after Kalidou Koulibaly had cancelled out former Chelsea forward Willian’s opener for the hosts.
Felix was shown a straight red card by referee David Coote in the 58th minute for a studs up challenge on Kenny Tete before Carlos Vinicius headed in a winner 17 minutes from time.
Chelsea have a mounting injury pile up which was added to by Denis Zakaria’s early withdrawal in the second half and have now lost seven of their last 10 games across all competitions.
Potter accepts Felix’s dismissal was the right call and it changed the complexion of the game.
"It was a forwards' tackle. There was no malice in it but I understand why it was a red," Potter told BT Sport of the Portugal international's lunge on Tete.
"It is another blow for us; the hits keep coming at the moment. [Joao Felix] was really good. You could see his quality in the game so it is doubly disappointing for us."
"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," Potter said.
"Second-half I think we responded well and then the red card changes the game. It makes it a little more difficult for us.
"But I thought the application when we went down to 10 was really good. I'm disappointed with the [winning] 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."
