Saracens could be without England back-row Billy Vunipola for the first month of the Premiership season as he recovers from shoulder surgery.
Vunipola, who has 34 international caps, had to withdraw from this summer's British & Irish Lions tour of New Zealand with the same injury.
The 24-year-old missed four months last season with a knee injury but returned to action in March.
"He's in great condition," said director of rugby Mark McCall.
"Billy's due back some time in October, but in true Billy style he'll make it back considerably before that. I'll be told by the medics when we can pick him but it won't be long."
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McCall could also be without prop Mako Vunipola, hooker Jamie George, fly-half Owen Farrell, forward Maro Itoje and back Liam Williams in time for the Premiership opener against Northampton on 2 September.
"Someone like George Kruis didn't play in the last two Lions Test matches, others missed a bit of rugby," McCall continued.
"With Mako (Vunipola) and Owen (Farrell) we have some tough choices to make.
"As a club we're not looking to get our pound of flesh. We're looking at the welfare of the player.
"I'm trying to make good choices based on good reasons as to when they come back."