Chelsea must wrestle back control of their season in Tuesday's Champions League semi-final at Atletico Madrid, according to Nemanja Matic.
Midfielder Matic admitted Chelsea surrendered all the power in the Barclays Premier League title race with Saturday's 2-1 home defeat to Sunderland.
Loan star Fabio Borini's penalty sealed Sunderland's Stamford Bridge victory on Saturday, handing the striker's parent club Liverpool the upper hand in the title battle.
Chelsea can expect contact from the Football Association on Tuesday over Ramires' apparent elbow in the face of Sunderland's Sebastian Larsson that went unpunished, and assistant coach Rui Faria's sending off for confronting fourth official Phil Dowd.
Matic said Chelsea can ill afford to bemoan their Black Cats defeat if they want to salvage their silverware dreams.
"I can say that we gave our best, I saw after the game that every player was sad because of the result," the 25-year-old told Chelsea TV.
"We tried, we fought until the end for the result, until the last minute, and we were unlucky not to win.
"Everybody knew how important it was for us, this game, but that's football.
"Now we can't do anything, we have to look forward, get focused on the Champions League, because as you know the Premier League title is going to be difficult to win."
Jose Mourinho suffered his first home Premier League defeat in 78 games on Saturday, and Chelsea are yet to face leaders Liverpool at Anfield on April 27.
Former Chelsea midfielder and Sunderland boss Gus Poyet admitted winning at his old stomping ground proved a "special" moment, and may even sway the title destination.
"It could be the key moment for the title," said Poyet, who spent four years at Stamford Bridge in his attacking midfield heyday.
"Everybody's going to be talking about Fabio (Borini) now because he's a Liverpool player.
"He's going to have a few digs from a few friends from Liverpool that's for sure, but I can assure you that we played only for Sunderland, we didn't play for anyone else."
Chelsea will hope goalkeeper Petr Cech will recover from the virus that ruled him out of the Sunderland defeat in time for Tuesday's Atletico trip.
The Blues will also sweat on the fitness of midfielder Eden Hazard, who will need to train on Monday to have any chance of making Mourinho's match squad for the Madrid battle.
Brazilian midfielder Ramires could well have played his last Chelsea game this season too, after appearing to strike Sunderland's Larsson in the face.
Ramires' strike was missed by referee Mike Dean, and the fact the official took no action leaves the door open for the FA to impose a charge.
With his two prior red cards for the season, Ramires could be facing a five-match ban, and that would end his campaign prematurely.
Chelsea assistant coach Faria can also expect FA censure after being sent off for overzealous criticism of fourth official Dowd.
Blues manager Mourinho had to restrain Faria as he lost his cool, even grabbing his assistant by the hair.