The injury-ravaged Wasps will play in Belfast on Friday, just days after facing Saracens at Allianz Park on Sunday, a game they lost 38-19, and the scheduling has not gone down well with Dai Young's side.
Young, who was without 15 players against Sarries, said: "It's not ideal by any stretch of the imagination.
"There is very little we can do about it. We've known for a number of weeks what was the case and we've just got to get on with it. It's far from ideal, obviously, and we just have to deal with it."
However, the European Professional Club Rugby (EPCR) said they "look to avoid" such issues but it was "not always possible".
"EPCR's fixture schedule is drafted in consultation with, and is given approval by, Premiership Rugby, the Pro14 and the LNR [French league]," an EPCR spokesman said.
"Champions Cup and Challenge Cup pool stage fixtures can only be confirmed following the announcement of the fixture schedules for the three professional leagues."