Ireland centre Robbie Henshaw has expressed his belief that this weekend's Six Nations clash with Wales will be the "toughest" yet for him and centre partner Jared Payne.

The duo will pair up at international level for just the fifth time in Cardiff and face the experienced duo of Jamie Roberts and Jonathan Davies, who boast 115 caps between them and have started 38 Tests together.

Henshaw acknowledged that he and Payne would need to be at their best to win that battle as Ireland look to maintain their challenge for a Grand Slam in this year's tournament.

"I think it could definitely be the toughest test for me and Jared. Wales are very direct but also they run decoy lines with Roberts coming up, only to throw it out the back and go wide. It's going to test us big time, so we've got to be prepared and stay connected in defence, and just keep our communication up all day," Henshaw told reporters.

"I think the Welsh centre partnership is up there with one of the best in the world. They have a really physical threat and massive size in that 10, 12 channel from Jamie Roberts, and then a very good ball player and direct runner in Jonathan Davies.

"They are going to test us big time this week but we are fully prepared for what they are going to throw at us. We'll have to get off the line quickly in defence and shut down their space and options as early as we can. We'll look to get into them early, and we won't hold back."

Should Ireland beat Wales this weekend then they would clinch the Grand Slam with victory in Scotland on March 21.