Carlos Moya's chances of playing at the Australian Open are in doubt after a serious ankle injury forced him to retire from the men's final against Lleyton Hewitt at the adidas International.

The Spaniard landed awkwardly on the outside of his right ankle attempting to save break point at 3-3 in the opening set, with the early prognosis being a bad sprain at best.

There are fears the 27-year-old could have suffered a fracture and he was immediately taken to hospital for an X-ray.

Moya is seeded seven at the Australian Open, which starts in Melbourne on Monday, and has been drawn to face American James Blake in a hotly-anticipated first-round clash.

He attempted to play on after extensive strapping was applied by tour trainer Bill Norris but could only hobble around the baseline.

And with the score at 4-3 and 40-15 - his point courtesy of a ripping winner - Moya conceded defeat.

"Lleyton was playing very well and even at 100% it was going to be tough to beat him, so congratulations," said a disappointed Moya afterwards.

"I hope I am going to get better for next week."

Moya was arguably the form player in the men's draw after winning his opening tournament of the season in Chennai and breezing through to the final here without dropping a set.

"I hope it's not going to be that bad but it hurts a lot," Moya said.

"There was no way I could (have played on), I couldn't even walk.

"It's disappointing, but these things happen in tennis. I was playing very well, I was very confident.

"The match was pretty open and it's a pity to end this way."

Hewitt fears the Rebound Ace surface, the same that is used at the Australian Open, can cause ankle injuries because it heats up in the sun.

"It's an extremely hot day out there today and on court it would be up towards 60. It gets hot, it gets sticky," he said.

"We've seen, the ones I can remember when I was younger, (Gabriella) Sabatini, (Mark) Woodforde, they sprained their ankles really bad at the Australian Open on hot days.

"It's awkward. It is partly because of the court as well."