TOMMY O’BRIEN is the big winner from Leo Cullen’s Leinster shake-up as the Blues host Glasgow Warriors tonight. And head coach Cullen insists the wing deserves his chance after so many false starts. O’Brien, 26, will make his first Champions Cup start in tonight’s last-eight clash after getting the nod ahead of Jamie Osborne. But it is not the first time he has been selected to feature from the off. He was also picked for the win over La Rochelle in January but had to withdraw through injury on the day of the game. And that, unfortunately, has been a regular occurrence as a result of hamstring issues that first troubled him in his school days. Cullen said: “When you’ve got a guy who has serious speed and power, you’re probably more susceptible to picking up soft tissue injuries. The slower people are not as cursed as much. He has real intensity to what he delivers on a week-to-week basis. His attention to detail is great, Tommy, he works very hard on all aspects of his game.” O’Brien has sought outside help for his hamstring issues as, on the advice of legendary Leinster and Ireland out-half Johnny Sexton, he paid his own way to Qatar last year to work with physio Enda King. And while he has had setbacks this season, Cullen has been keen to get him into action. A sprint hurdler as a teenager, O’Brien won national medals. And he brought the same speed to rugby where his 6ft and 14st physique means he is harder to take down. Cullen added: “There are plenty of guys like him but in terms of their top-end speed . . .  “During the week I actually met his sprint coach randomly who coached him when he was in school. I gave him a pleasant surprise that he was starting on Friday. “I hope it goes well and we’re excited to see him go now. “He has massive moments in games whether in attack or defence. He’s got genuine speed. “He’s got a good bit of edge and you can see in a lot of Glasgow games, there is a good bit of niggle and edge. “I hope he goes well, he deserves this opportunity.” O’Brien is included for what is likely an Ireland audition ahead of the summer tour to Georgia and Portugal. The former Ireland Under-20 captain is one of six changes. Also in from the start are front rows Cian Healy, Rónan Kelleher and Tadhg Furlong. Max Deegan comes into the back row and Jordie Barrett has been chosen in the centre. Caelan Doris drops to the bench along with the front row that started against Harlequins, while Cullen revealed that Ryan Baird is absent from the 23 due to a short-term injury. Having walloped Quins 62-0 at Croke Park last Saturday, Leinster are in fine form. Cullen claimed his raft of changes was about sharpening minds. He said: “That’s some of the selections, making sure we’ve guys who are fresh mentally coming into it. “They know there’s other guys who are beating the door down to get the opportunity. “There’s genuine excitement to get out playing again. “It’s a genuine excitement to play again, we’re at the Aviva and the atmosphere has worked really well there. It’s a great ground, nice time of year and an enjoyable time to play. It’s an incredible privilege and lads just need to savour the moment.” Warriors will be without Zander Fagerson after the Scotland star suffered concussion following last week’s Leicester win. Sam Talakai starts, with Patrick Shickerling added to the bench.Glasgow head coach Franco Smith said: “Zander is unique in what he does. He plays an integral part. But I’m confident we have other players that can also do an important role.” The South African added: “Look, we all know everything about Leinster. There’s no need to make more of them than what they already are. I don’t think we need extra motivation. “Going to the Aviva Stadium and playing arguably the best club team in the world is motivation enough.” LEINSTER: H Keenan; T O’Brien, G Ringrose, J Barrett, J Lowe; S Prendergast, J Gibson-Park; C Healy, R Kelleher, T Furlong; J McCarthy, RG Snyman; M Deegan, J van der Flier, J Conan. Reps: D Sheehan, A Porter, R Slimani, D Mangan, C Doris, L McGrath, R Byrne, R Henshaw.