Arsenal will be without goalkeeper Petr Cech and centre-back Laurent Koscielny for Saturday's trip to Tottenham Hotspur, manager Arsene Wenger revealed after Wednesday's 2-1 loss to Swansea City.
"Cech got a muscular problem at the end of the game," Wenger said. "He will not play on Saturday. I have full faith in (David) Ospina."
On Koscielny, he added: "He has a calf problem as well. He will not play on Saturday."
The double injury blow will have blackened Wenger's mood yet further after a result that left Arsenal six points below Premier League leaders Leicester City in third place.
It was Arsenal's third defeat in a row, after previous losses at the hands of Barcelona and Manchester United, and saw them booed off by their own fans at the Emirates Stadium.
Wayne Routledge cancelled out Joel Campbell's early opener for Arsenal before Ashley Williams bundled in a 74th-minute winner.
"It is a very unlucky defeat because we created many chances and we were unlucky in our finishing," said Wenger, whose side hit the woodwork three times.
"The two shots on target they had in the whole game were the two goals. It's a very disappointing result and the players are very down. We have to respond to that.
"It looks a bit like a confidence issue. We have to focus on our job and come back, reminding ourselves that we have some quality as well. Analyse it well and bounce back. We have a big game in three days.
"At the moment I am more worried about our results (than the title race). We just lost three games and that is always a very difficult moment for the team.
"At the moment we don't dream, we are realistic. We must come back to what we do well and do the basics."
NOT IN THE MOOD
Wenger defended his decision to send Danny Welbeck on for Campbell in the second half, a move that drew derision from Arsenal fans and cries of "You don't know what you're doing!"
"Campbell has not played for a while and he started to tire," the Frenchman said. "He played against a very young left-back and I thought Welbeck could give him some problems with his runs behind.
"These kind of decisions don't mean that Campbell did badly. I think he did quite well tonight (Wednesday), but there was room on that flank to be very dangerous with pace.
"We have to take the fans on our side. They were ready to support us tonight.
"They were quite good, but we faded in the game and you could see in the last part we had a lack of movement to create dangerous situations.
"We will not talk about titles tonight. I'm not in the mood. It's a big disappointment."
Swansea's win was all the more remarkable given they were without head coach Francesco Guidolin, who had been admitted to hospital with a lung infection.
His deputy Alan Curtis, who made six changes, said: "I've not spoken to him, but I had a voicemail to say how delighted he is.
"As far as I know, it's a lung infection, and he stays in hospital for the next couple of days, (it) remedies itself quite quickly, and he travels to Swansea on Friday.
"He's been struggling for a week or so, but he's turned up for training and helped pick the team with the changes.
"We know we could have faced criticism, but it wasn't change for change's sake. There's nobody guaranteed a place.
"I do think we'll stay up. We have enough in the changing room. The squad is there and if we can pick the right team and the right shape, there's no reason why we can't get the results between now and the end of the season."