All Blacks pair Sonny Bill Williams and Ma'a Nonu believe Brian O'Driscoll's return makes Ireland a much more dangerous prospect.

Williams, who has enjoyed a fine Super Rugby season with the Chiefs, is pushing Conrad Smith hard for a starting position in midfield alongside the imposing Nonu.

O'Driscoll, who missed four months of the season after shoulder surgery, has long been considered Ireland's main threat and Williams does not expect that to be any different when the sides meet in the first Test on Saturday.

"O'Driscoll is always the danger man. Absolutely. He's done well since he came back," said Williams.

"It's going to be a tough challenge but hopefully we can play a style of footie that is entertaining but a winning style as well."

"I'm looking forward to it, getting that black jersey back on. But the Irish are playing some good rugby and both Irish teams (Leinster and Ulster) in the Heineken Cup Final."

Nonu, who moved from the Hurricanes to the Blues in Auckland this season, also anticipates a strong challenge from O'Driscoll.

"O'Driscoll is going great," he said.

"He always turns out. He's such a great player, that I admire. I've been watching him for a long time and always seems to turn up at the right time, especially for Leinster. The older he gets, the better he gets. Really."