Both players have travelled to San Sebastian with a 30-strong squad after picking up injuries during the Sharks' 29-21 victory over London Irish at the Madejski Stadium on Saturday.
"Cueto's more of a doubt," said Sale media and PR manager Dave Swanton. "It's not a break and not ligament damage. Mark's a fighter and he wants to play."
The England winger is nursing a swollen ankle after tripping over an advertising triangle near the pitch while trying to catch a ball. Robinson had to be substituted after 18 minutes after he took a heavy knock on his hip.
Half-back Richard Wigglesworth has recovered from a hip injury and second row Christian Day is available again after damaging his hand.
The club has taken an experienced team of medical staff to Spain to give themselves the best chance of naming a full-strength side.
Swanton added: "Our physios are top notch."