Glasgow Warriors head coach Dave Rennie believes he saw enough at Scotstoun yesterday to encourage the belief that his side can still reach the Heineken Champions Cup quarter-finals in spite of losing their opening match at home.

Unusually their pool opened with two away wins as last season’s second-tier Challenge Cup winners Cardiff Blues also shocked French newcomers to the competition Lyon and ahead of next weekend’s trip to Wales.

"You know Saracens are going to be there in the end, Cardiff had a good win away in Lyon (so) they'll be tough next week but if we can win away we'll be back in the race,” he said.

“Last year Scarlets lost their first couple and ended up in the semis. We'll dust ourselves off, look at what we did well, be clear on where we have to be better and have another crack at Cardiff."

While history indicates how difficult it will now be to get to the knockout stages, the New Zealander reckons the way they competed with odds-on pool favourites Saracens, the champions in two of the past three years, showed that his men have improved significantly since last year when the lost their first five pool matches to exit the competition without making any sort of impression.

“"Our setpiece was strong, our scrum was dominant early (but) they started sharing across and (Maro) Itoje was joining the front row (and) we didn't get the same dominance,” he said, pointing to the way they had forced the English champions to make adjustments.

“Our setpiece defensive lineout is a lot better, we're stopping mauls, they're a bit of a juggernaut in that area. We're happy with that.

“Guys like Matt Fagerson, he's not the biggest of men but he's got great footwork and his ability to get in behind gave us opportunities. We did talk about going through the middle and picking off rucks but we didn't do that. We also talked about using the short side where we could attack their big men. We didn't do that early."

The ferocity of the battle was reflected in a string of injuries suffered by the visitors with both their influential Vunipola brothers, Billy and Maka, forced to retire from the fray with arm and calf injuries and Nick Isiekwe also departing with a leg injury, while Itoji and Jamie George suffered broken noses and Mark McCall, the Saracens director of coaching, acknowledged that Glasgow finally look like a force to be reckoned with in Europe.

“It was a very important win. What we are most pleased about is how we scrapped when we needed to scrap,” he said.

“They defended brilliantly, we struggled for quick ball, something we really struggled to get a lot of the time though there were times we did. They are a dangerous team as well and we had to scramble back a few times to stop some of those breaks.

“We knew the improvement they had made, how dangerous some of the individuals were, the quality of Adam Hastings who can make something out of nothing though I thought for the most part we covered him pretty well. They are a good side, they are well coached and have quality players. There are no surprises for us, it was a very good win.”