The Blues looked on course to move three points clear of Liverpool than to Romelu Lukaku's second goal in as many games, yet the Seagulls stole a point in stoppage time courtesy of Danny Welbeck's header.

Chelsea has dropped 11 points from leading positions in the Premier League this season – more than it did in the whole of last season (10).

The European champion is without a number of first-team players due to COVID-19 and injury, with Reece James and Andreas Christensen adding to Tuchel's woes after sustaining problems against Graham Potter's side at Stamford Bridge.

"We don't know what we can demand from players after long injuries and COVID-19; I don't know what they are capable of doing," a visibly frustrated Tuchel said. "This is where we are and we need to adapt to the demands in this situation. I know what it is. I competed heavily for the win against Brighton but I simply don't know what I can expect from my players now.

"We have never done something like this. We simply have to see what we get."

Chelsea remains unbeaten against Brighton in the Premier League (P9 W6 D3); only against Portsmouth (14) and Hull (10) have the Blues played more games in the competition without losing.

That was scant consolation for Tuchel, though, who said his side should have been given a penalty when Christian Pulisic was brought down inside the area.

"It is too much, sometimes it is too much," Tuchel said.

"Brighton had nothing to lose and played with confidence. We had huge, huge chances. Normally I would never say it, but we have a 100 per cent penalty against Pulisic.

"We have a horrible decision for a penalty from the referee for 2-0. It wasn't even checked. Everything against us.

"We knew before that this would be a tough match, I have not seen many teams play a nice game against them."

Chelsea is next in action on Monday (AEDT) when Liverpool travels to Stamford Bridge in what is a game both sides might already consider a must-win as they look to keep pace with Manchester City.