Watch: Leo Cullen is wary of challenge Ulster present Leinster at the Aviva Stadium in the European Champions Cup
It is only the second meeting in the knockout stages between Leinster and Ulster in Europe when the sides meet at the Aviva Stadium on Saturday.
Defending champions Leinster are favourites to progress to the semi-finals but head coach Leo Cullen is wary of the challenge Ulster present to the continued defence of the trophy
