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."
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.