Melbourne Rebels coach Damien Hill faces a tricky decision over whether to favour Kurtley Beale or James O'Connor as his playmaker.

With both versatile Wallabies back to full fitness, Hill faces an interesting poser over how best to utilise their skills, and he is not giving anything away just yet.

"James can play wing, 15, 12, 10 and KB (Beale) can play 10 and 15 as well," Hill told AAP.

"It's going to be what's best for the team. They combine really well so they will be together out there and the two main voices," he added.

O'Connor impressed in the role on the Wallabies' 2011 year-end tour, but was cut down by injury last year and spent most of his time on the sidelines, whilst Beale replaced the injured Quade Cooper as Australia's flyhalf last year and grew into the position admirably as the season progressed.

Hill admitted that he is still not sure what his strongest starting line-up is, and will rely on warm-up games against the Waratahs and Hurricanes to settle on the most effective combination.

"Competition for spots this year is the most we've had which is a fantastic position to be in, even if it creates a few headaches," Hill said.

"The trial matches will be used to fight for positions so they'll be very valuable for us.

"Thankfully we've got 34 of our 35 fit and ready to go so we've got a lot of combinations and we're working through how we're going to play them," he added.