Leinster have been handed some timely injury reinforcements with the news that Tommy O'Brien and Ed Byrne are back in training and may be in contention for Friday's BKT United Rugby Championship clash with DHL Stormers.O'Brien could make his first appearance in 10 months after recovering from a serious ACL injury, while Byrne is also in the reckoning for the first time this year after he suffered a knee injury in December.The return O'Brien and Byrne is well-timed as Leinster continue to come to terms with a bruising Ireland Six Nations campaign that has side-lined some of their biggest stars.Garry Ringrose and Hugo Keenan will continue to follow the Graduated Return to Play Protocols with Leinster Rugby, while Johnny Sexton will have a scan today on a groin injury picked up in Saturday's victory over England.Jamie Osborne is also set for a spell on the sidelines after he sustained a knee ligament injury in Leinster's victory over Edinburgh two weeks ago.Elsewhere, Ulster have injury concerns of their own ahead of their last 16 encounter against Vodacom Bulls at Kingspan Stadium.Iain Henderson continues to recover from surgery on a broken arm, while Will Addison is doing likewise after he suffered a broken leg in November.The Northerners' other long-term absentee Marty Moore also remains sidelined with a knee injury.