England fly-half Owen Farrell could be set to make his first appearance of the season when Saracens face Harlequins at the Twickenham Stoop on Saturday.
Farrell picked up a back injury over the summer and has missed all three of the champions' Aviva Premiership victories so far this term.
Director of rugby Mark McCall insists the 24-year-old may be ready for the London derby at Twickenham Stoop, but Farrell's England team-mate George Kruis is almost certainly out.
"Owen has trained and maybe has a chance for the weekend, we'll see how he is after Tuesday's training session. George didn't train, so he's unlikely, but we'll see how he is," McCall said.
"Both injuries are a little bit indeterminate. They're not those types of injuries where you have two weeks and you're back. They're both back injuries."
Flanker Will Fraser could make his comeback from a double hip injury against Bristol on Friday week.