Venue: Ravenhill, Belfast Date: Friday, 21 December Kick-off: 19:05 GMT Coverage: Live on BBC TWO NI and BBC Sport website Pro12 leaders Ulster have made four changes for Friday night's Irish derby clash against Leinster at Ravenhill. Craig Gilroy and Neil McComb replace injured pair Tommy Bowe and Dan Tuohy while Luke Marshall and Robbie Diack also come into the side. Leinster have made eight changes following their Heineken Cup defeat by Clermont Auvergne last weekend. Cian Healy, Sean Cronin and Michael Bent form a new front row with Kevin McLaughlin also among those drafted in. It wouldn't phase me to line out against my home province, I just want to perform at senior level  Alan O'Connor Ulster lock Noel Reid, Andrew Conway, Brendan and Devin Toner complete the new faces for a Leinster side which shows a mixture of youth and experience. Hooker Richardt Strauss misses out with a medial ligament injury, picked up against Clermont, which will keep him out for four weeks. Ulster centre Luke Marshall takes over from Paddy Wallace while flanker Robbie Diack replaces Roger Wilson. Nick Williams moves from blindside flanker to number eight is the only positional switch from the Heineken Cup defeat by Northampton. Four players have been called up to the bench - Rob Herring, Adam Macklin, Alan O'Connor and Adam D'Arcy. If he comes on, the game will be Alan O'Connor's first appearance for Ulster. The 20-year-old Dubliner joined the Ulster Academy in the summer. He played his club rugby at Skerries until he was 18, before playing for two years at UCD. He was part of the Leinster sub-academy before joining Ulster in July. "I have come up here to play rugby and hopefully I will get a chance on Friday night," said O'Connor. It wouldn't phase me to line out against my home province, I just want to perform at senior level - and playing against the European Champions is just about as competitive as it gets. My dad has tickets for the game and will be making the trip up from Dublin for the match. He is a proud Leinsterman, but I am not sure who he will be cheering for tomorrow night. Ulster: J Payne; A Trimble, D Cave, L Marshall, C Gilroy; P Jackson, R Pienaar; T Court, R Best, J Afoa, I Henderson, N McComb, R Diack, C Henry, N Williams. Replacements: R Herring, C Black, A Macklin, A O'Connor, R Wilson, P Marshall, P Wallace, A D'Arcy. Leinster: N Reid; A Conway, B Macken, G D'Arcy, F McFadden; I Madigan, E Reddan; C Healy, S Cronin, M Bent, L Cullen, D Toner, K McLaughlin, S O'Brien, J Heaslip. Replacements: A Dundon, H van der Merwe, J Hagan, T Denton, R Ruddock, I Boss, A Goodman, A Byrne.