Remember they told us not to worry about Sean O’Brien? Well…

Sean O'Brien was definitely in the selection mix for this weekend's Champions Cup tie with Castres, Leo Cullen told us last Friday.

Earlier this week we were told Leinster were hopeful of including him in the travelling party. "We didn't take any risks with him," said Cullen. "He should be available next week." This morning came confirmation - O'Brien will play no part in this weekend's games. With no Guinness PRO12 fixtures scheduled for next weekend, O'Brien will be without any game time for a month were he to make Joe Schmidt's Ireland XV to face Scotland. While he is not joining the list of injured Irish senior stars [below] the latest team news from Leinster is a worry. Cullen attempted to assuage any fears that O'Brien could be out for longer than expected, last week, when he addressed the matter of him missing the Montpellier game with a tight calf. Queried after that comfortable home win over the French side, Cullen suggested O'Brien would be keen to feature this weekend. O'Brien is willing but his body is not able. Jack Conan and Josh van der Flier are in at blindside and openside for Friday's encounter at Stade Pierre-Antoine. https://twitter.com/leinsterrugby/status/822013501610737665 The fact that O'Brien is missing out on two big Champions Cup games in a row will do him no favours in terms of making Joe Schmidt's Ireland XV. Should O'Brien shake off is calf issues, he will be lacking in match fitness. Being able to step into a Test match team is something that definitely played on Schmidt's mind last season. He said:

"We feel the pace of the [New Zealand] game will be very, very quick. We tried to select the guys [Jordi Murphy and Josh van der Flier] who we felt were match-fit and ready to go."

The fact that O'Brien was forced to withdraw from the Ireland team to face Australia, last November, at late notice does also not bode well for his chances. Schmidt names his Six Nations squad, for the opening rounds, on Sunday.