Arsenal manager Arsene Wenger expects midfielder Aaron Ramsey to return from a thigh problem in four weeks.
Ramsey lasted just 16 minutes of the 4-0 FA Cup victory over Hull City on Tuesday before he was forced to come off after pulling up injured.
Early reports speculated that the Wales international could face close to two months on the sidelines, placing his chances of returning to full fitness before Euro 2016 in doubt.
But while Wenger admits the injury is more severe than he initially feared, he hopes to see the 25-year-old back by the middle of April.
"No, I don't think he's out for the season," he told the media on Friday. "The clinical signs are quite positive.
"As a start I would say four weeks. It's a bit worse than I thought at the time. I thought it would be just a precaution and he would be available for Sunday."
Wenger hopes to have central-defensive duo Gabriel and Per Mertesacker available for the quarter-final clash with Watford after they suffered knocks against Hull.
"Gabriel and Mertesacker should be available," he said. "Laurent Koscielny is not far off. He has to train tomorrow, then we'll decide if he is fit to play."
