Leinster fans could be worried by the glaring omission from the side to face Montpellier

Lets hope it isn't serious.

Leinster have announced their side for their crucial Champions Cup clash with Montpellier. A win here, against their nearest group rivals, will likely secure passage to the quarter-final stages of the tournament. So you would expect that Leo Cullen would field his strongest line-up for this clash. Unfortunately for Cullen and Leinster, Sean O'Brien has picked up an injury this week in training and will miss out on the action at the RDS. https://twitter.com/leinsterrugby/status/819514307494879232 The Tullow Tank did feature in Leinster's last two matches against Ulster and Zebre so it will come as a disappointment that O'Brien has picked up an injury, especially as he looks to gain a bit of momentum going into the Six Nations. Leo Cullen has stated in today's press conference that O'Brien felt tightness in his calf and should be fine for next week's clash with Castres, Leinster's final Champions Cup match. Lets hope that this is the case.