Arsenal are still waiting to find out how long Aaron Ramsey will be sidelined for with a thigh injury, but manager Arsene Wenger says centre-backs Per Mertesacker and Gabriel Paulista are both fit to play.
The trio all suffered injuries in Arsenal's 4-0 win over Hull in the FA Cup on Tuesday -- Ramsey with a thigh problem just 15 minutes after coming on as a substitute.
Wenger said after the game he was worried that the Wales midfielder had a thigh strain, and Ramsey was set to undergo further scans on Thursday.
"There is a small alert, we don't know how bad it is," Wenger told Arsenal's official website.
Mertesacker sustained a cut to his eye after clashing heads with an opponent in the first half, while Gabriel limped off with a hamstring problem after the break.
But Wenger indicated that both should be available for Sunday's FA Cup quarterfinal against Watford at the Emirates.
He said: "Mertesacker and Gabriel are very positive, there is nothing wrong there, they are both good."
Meanwhile, Laurent Koscielny still faces a fitness test after missing Arsenal's last two games with a calf problem.
"He is not far, he will have tests until Sunday, but it could come too soon. He has a little chance," Wenger said.
Arsenal will need their defenders back fit as they have three crucial games coming up in a seven-day span.
The FA Cup quarterfinal is followed by a trip to Barcelona in the Champions League on Wednesday and then an away game at Everton in the Premier League the following Saturday.
Arsenal are already without injured goalkeeper Petr Cech, who is out for up to a month with a calf problem.
They finished the game at Hull with a centre-back pairing of Calum Chambers and Nacho Monreal and holding midfielder Mathieu Flamini playing at right-back.