Ulster host the English club at the Kingspan Stadium in Round 3 on Saturday and then travel to Twickenham Stoop on December 13.

"It's the back-to-back games that are the big ones," the Irish international told BBC Northern Ireland.

"Last year we went away to Scarlets and put in a huge performance, and then beat them at home as well, which really gave us a lot of momentum. If we can do the same, then that will put us in a brilliant position.

"We have good momentum now and it is important that we continue it and that we play with confidence."

The 29-year-old has enjoyed a terrific start to the European season, scoring two tries and racking up 25 points as the Irish province narrowly defeated Bath Rugby 17-16 and ASM Clermont Auvergne 18-13, although he admitted his performances can be improved.

"In some games I've kicked well but not passed as well, so I've high standards that I try and meet," Cooney added. "I still think that I have a lot more to give and a lot more to improve.

"I missed an easy kick against Bath and I knew if I responded poorly and missed another kick, then we would lose, so I always say that is about winning the next moment."

You can watch Ulster Rugby v Harlequins, live on BT Sport and beIN SPORTS on Saturday from 15:15 GMT.

Ulster Rugby scrum-half John Cooney has labelled his side’s successive matches against Harlequins in the Heineken Champions Cup as “the big ones” as the Irish province seek to strengthen their position at the head of Pool 3.