The British and Irish Lions have been hit by an injury blow ahead of next Saturday's second Test against Australia in Melbourne.
The Lions announced that prop Alex Corbisiero is being "treated and assessed" for a calf muscle injury.
Ireland prop Tom Court, meanwhile, has been called into the squad ahead of Tuesday's game against the Melbourne Rebels. Ulster forward Court is currently in his home city Brisbane following Ireland's North American tour, and he will join up with the Lions squad on Monday.
Corbisiero, who joined the Lions tour as front-row cover earlier this month from England's two-Test trip to Argentina, went off early in the second half as the Lions beat Australia 23-21 at Suncorp Stadium on Saturday.
Mako Vunipola - a probable second Test starter if Corbisiero is ruled out - has been withdrawn from the match-day 23 for the Rebels clash.
On the other side of the coin, centres Manu Tuilagi and Jamie Roberts are in contention after recovering from respective shoulder and hamstring injuries, along with wing Tommy Bowe, who has recovered rapidly after suffering a broken hand against Queensland Reds 15 days ago.
Reflecting on the encouraging comebacks of Bowe and Tuilagi, Gatland said: "To have Tommy and Manu fit and back is a great compliment to the medical staff. Tommy is fit for Saturday, he's running, but the more time he has to heal the better.
"The surgeon said that that injury is normally a six to eight-week injury, so to be fit in three weeks is magnificent."