Leicester Tigers v Ulster, Welford Road, 8pm.

I give Ulster a great chance. It's a huge opportunity for them, they dropped down to the Challenge Cup having not made the last 16 in the Heineken Champions Cup. They haven't won a trophy in 15 years.

Leicester are not the team they were a number of years ago. They are mid-table in the Premiership.

They did beat Connacht in the last 16, Connacht beat Ulster in the Rainbow Cup last weekend so it should be tight.

I love Ulster's 9-10-12 combination of John Cooney, Billy Burns and Stuart McCloskey. Iain Henderson is back firing. He hasn’t played a whole lot of games for Ulster this year.

I think Ulster are good enough to go to Welford Road and make the final, which would be a brilliant achievement for them.

La Rochelle v Leinster, Stade Marcel-Deflandre, Sunday, 3pm

It's a fascinating game, the tie of the weekend for me.

There’s a lot of focus on Ronan and Jono Gibbes but, in many respects, that irrelevant. People forget that Ronan has been out of Ireland for nine years; Jono Gibbes hasn’t been involved with Leinster since 2014. It’s a dream tie for O’Gara.

Leinster are a champion side for a reason. You just look at their form since the end of the Six Nations.

In the two games that really mattered: they blew Munster away in the final of the Guinness Pro14 and then in a game people thought they might struggle in, against Exeter, champions of England and reigning European champions, they went 14-0 down, they lost Johnny Sexton and yet they found a way to win and that’s what champion sides do.

It’s going to be a very tight affair, but I think Leinster have that champion quality.

The one thing that might be in the back of their minds is their nemesis in Europe in the last couple of years has been Saracens. They have a huge physical forward unit that took them on and pressurised them.

La Rochelle will have a similar base to work from. Whether they’ll be good enough or not to do that...I still fancy Leinster.

Donal Lenihan was speaking on RTÉ's Morning Ireland

Follow La Rochelle v Leinster (Sunday, 3pm) and Leicester v Ulster (Friday, 8pm) via our live blogs on RTE.ie and the RTÉ News app or listen live on RTÉ Radio 1's Sunday Sport and RTÉ Radio 1 Extra.