Leinster have been left to count the cost of their strong representation in the Ireland squad over the last month, as Leo Cullen faces several injury headaches ahead of this weekend's return to the United Rugby Championship.

Player loads will be managed for Saturday's game against Ulster at the RDS, but Ireland internationals Johnny Sexton, James Ryan and Jack Conan have been ruled out.

Captain Sexton will be unavailable for three to five weeks with knee and ankle issues, while vice-captain Ryan will follow the graduated return-to-play protocols after suffering another worrying head knock in the first-half of Ireland's win over Argentina on Sunday.

Conan pulled out of the starting team with a quad injury and will be further assessed.

Jamison Gibson-Park is also struggling with a thigh problem, but hasn't yet been ruled out of the Ulster clash.

In a further double blow, the luckless Conor O'Brien (hamstring) is facing several months on the sidelines, with Dave Kearney (back) ruled out for a few weeks after both backs were injured in last week's Leinster 'A' game.

Meanwhile, Thomas Clarkson returned to action for Trinity in the Energia All-Ireland League last weekend following a recent hamstring problem.

Ireland back-row Will Connors (knee) is set to make a welcome return to training this week, and will be further assessed before the Ulster game.

Michael Milne (calf) and Rory O’Loughlin (shoulder) remain sidelined.