Fly-half Richie Mo’unga has been cleared of a serious shoulder injury, but could miss New Zealand’s final World Cup warm-up match against Tonga on September 7, coach Steve Hansen said on Sunday.

Mo’unga fell heavily in a gang tackle midway through the second half of the All Blacks’ 36-0 Bledisloe Cup victory over Australia at Eden Park on Saturday and was immediately replaced.

Hansen said after the game the team’s medical staff was not overly concerned with Mo’unga’s initial diagnosis and the coach confirmed on Sunday that it was not that bad.

“Richie’s shoulder looks like an AC joint issue,” he told reporters in Auckland.

“Whilst it’s not long term, he’ll be sore for a couple of weeks. Hopefully no more.”

Hansen added the uncapped Josh Ioane could potentially join the squad for the match against the Pacific Islanders in Hamilton, but they would make that decision closer to the time.

The All Blacks have little depth at fly half beyond Beauden Barrett and Mo’unga with Loane named as the third-choice for the Rugby Championship.

The 24-year-old Loane did not make the official 34-man squad for the Bledisloe Cup but remained with the team to train with them in case of injury.

Hansen said he would name his final 31-man World Cup squad on Aug. 28 and after the performance of several players on Saturday against the Wallabies he acknowledged he would have some tough calls to make in the next 10 days.

Rookie wingers George Bridge and Sevu Reece both impressed after they replaced Ben Smith and Rieko Loane, while Patrick Tuipulotu may have done enough to earn a ticket to Japan with Brodie Retallick still recovering from a dislocated shoulder.

Former World Player of the Year Retallick is likely to be picked in the squad and given as much time as he needs to recover.

The All Blacks have precedent for such a strategy having selected Kieran Read in the 2011 World Cup squad despite the number eight suffering a bad ankle sprain just before the tournament.

He did not play until the final pool stage match against Canada.

Hansen, however, was pleased with where his side was in terms of injuries and selection issues as they seek a third successive World Cup title in Japan.

“Where we had question marks, you no longer have question marks,” he said.

“But in other ways it makes it a bit tougher too. There are always tough calls. Every time you name the team somebody misses out and it’s the end of their dream, and this is a pretty big one going to a World Cup,” added Hansen.

“We’ll have plenty of discussions between now and then, but a lot of the robust ones have been had. We’ve baked a lot of the cake, now it’s about getting it out of the oven and putting a bit of icing on it.”