Brumbies flyhalf's season ends

Brumbies flyhalf Matt Toomua has been ruled out for the remainder of the Super Rugby season with a serious knee injury sustained during the 29-26 defeat to the Sharks on Saturday.

The injury is a more serious reoccurrence of the one Toomua suffered three weeks ago against the Cheetahs, while scans have revealed a torn cruciate ligament in his left knee according to AAP.

The 22-year-old attempted a quick change of direction during the match, and his knee gave way leaving him in agony on the ground as play continued.

Brumbies coach Jake White has conceded that Toomua may have been rushed back from injury prematurely.

"It's funny - in coaching you always have to make some risks and we say the biggest risk is not taking a risk," White told AAP.

"He was ready to go. But it wasn't the right call to bring him back this week.

"One never knows. The reality is maybe we rushed him back, but we did the same with (lock) Leon Power and he's just gotten better and better."

The injury leaves Christian Lealiifano has the first-choice flyhalf and could open the door for more starting opportunities for NRL convert Joe Tomane.