The 22-year-old was one of four try scorers including Shane Horgan, Isa Nacewa and Shaun Berne as the holders controlled Scarlets from start to finish and ran out 32-7 victors.

And O’Brien – who featured during Ireland’s 15-10 win over world champions South Africa last month – insists next week’s return home fixture can’t come quick enough.

“We had opportunities in the first half and we let them slip and maybe our concentration wasn't as good as it should have been,” said O’Brien.

“We had to work very hard for the fourth try and we're happy with the performance in the first half, especially, but we needed to kick on and we didn't do that.

"We're looking forward to next week. Nowadays you know you have to have your line speed right and that approach never changes from week to week.”