However Glasgow captain Ally Kellock believes they can turn round the results of two narrow defeats and a draw in two pool games and a quarter-final, with both sides having recruited strongly over the summer.
Saracens have brought in the likes of New Zealand second row Chris Jack, but lock Kellock says his players are looking forward to facing the high-flying English club.
"Playing Saracens is a strange one because we know them so well from last year, but it is good that we competed with them last year and showed us at times that we could have won games even though they came out on top," said the Scotland lock.
"They are a wealthy club and can bring in world class players such as Chris Jack, but we have brought in quality as well with guys like Daryl Gibson who is also an All Black albeit from a different era.
"Daryl is like a lot of the guys such as Todd Blackadder because everything he does is very professional and that lifts training and lifts everybody’s game."
It is a difficult group with Saracens and Biarritz, while Kellock refuses to accept that Italians Viadana will be easy opposition the obvious focus is on the giants from England and France.
However Glasgow’s confidence has been lifted by reaching the Challenge Cup quarter-finals and a strong finish in the Magners League last season.
"Reaching the quarter-final last year was good for us, even though it was in the lesser competition. It gave us a taste for it, we are trying to grow rugby in Glasgow and when we did that we got a lot more press coverage in the latter stages which helps," he said.
"We are going all right this season too, home form is reasonable, but it is tough with players who have been away and a lot of new players, but they are all quality so it is up to us to get back to where we were at the end of last season when we were winning games regularly.
"I am looking forward to facing Chris Jack, that will be a good challenge, but even last year they had quality in the second row at Saracens.
"The Borders gave Biarritz a good run last year so the former Reivers guys have come in and told us about that, it will be good to have people in our team who have played against them."