Maria Sharapova fought back from a set down against Agnieszka Radwanska to claim victory on her return from injury at the WTA Finals in Singapore.

The world number three made her long-awaited comeback from leg and arm problems on Sunday and looked a little rusty in the opening set of her 4-6 6-3 6-4 triumph.

Radwanska took the opener with a decisive break in the ninth game, seeing two chances pass her by before finally finding a way through.

The Pole then held serve – despite some crisp passing shots from Sharapova – to move ahead, but it only served to spark her opponent into life.

Sharapova levelled thanks to two breaks in the second set and looked to be cruising to victory after another two in the decider, although she wavered in the closing stages.

Having allowed Radwanska back into the set in the eighth game with a break, Sharapova then fluffed her lines two games later as she double-faulted for the 12th time in the match.

After surviving two break points, Sharapova recovered to put herself on the brink of victory - eventuallly converting her second match point.

"This is my first competitive match since July so it's a big deal for me," Sharapova said in her on-court interview. "I didn't play my best today, sometimes that is not what matters, so I am happy to come through.

"It is great to get a win against a tough competitor, to be able to fight to the end and win, it means a lot to me."