"It's no use putting in a guy who will play perhaps only one Heineken Cup game," Gatland admitted. "We have some pretty clinical decisions to make at the club before Thursday."
England stars Fraser Waters, Stuart Abbott and Josh Lewsey, Wales hero Rob Howley, former All Black Craig Dowd are all on the injury list and Samoan powerhouse Trevor Leota has been in New Zealand sorting out his work visa.
Gatland admits that of the injured players, only Waters and Lewsey have much chance of appearing in Wasps' first Cup game against Biarritz Olympique.
"It's tough to go into Zurich Premiership matches with up to seven or eight international players missing, so I'm very pleased with two wins and two narrow losses," said Gatland after his side came from behind to beat London Irish 35-26.
"In the four games we have played, the other teams have been at full strength and it is about keeping faith with those young guys. "
If the injury list wasn't bad enough, Gatland says Wasps have been drawn in the toughest pool in the tournament - with double champions Leicester Tigers and dangerous French outfit Biarritz between his side and a spot in the quarter-finals.
"It's a very tough group," he said. "The seedings were done on domestic competition, not European competition, so the rankings sort of go out the window and we've landed a couple of very tough opponents.
"In a way, though, it's great preparation for an attack on the title. The team who emerges on top in our pool will have been in some very tough games and they'll be a big chance to win the whole thing. You have to beat the big teams at one stage, so why not in the Pool rounds? We're all looking forward to the Heineken Cup - it's the tournament everyone loves and it's the ultimate one to win.
"Having said that, we're concentrating on the Zurich Premiership, and it's healthy that there seem to be half a dozen teams in with a chance of winning the title. Every team in the Premiership thinks they can beat anyone else and that's a fantastic thing for any competition to have."