Gabriel Heinze has been fighting back from injury for six months

Heinze's initial estimate of returning in March from the ruptured cruciate ligaments that threatened to end his season, has proved to be optimistic.

A return before the end of the season may make the 27-year-old a contender for Argentina's World Cup squad.

United boss Sir Alex Ferguson said: "He could be back in April and possibly play before the end of the season."

Ferguson had written off Heinze for the season after he was injured in the Champions League tie against Villarreal in September.

Heinze has been missed at Old Trafford and sprang a surprise this week by announcing he may return "within a month", given the progress of his rehabilitation in Spain.

Ferguson added: "Gaby is on full throttle, his progress has been very good and he is training every day.

I think about the World Cup in Germany as the big final target for my rehab Gabriel Heinze

"He wanted a particular surgeon to do the operation, which he was entitled to request and, having made that decision, we felt he should have the rehabilitation in Spain so the surgeon was in complete control of the situation.

"The news that he could be playing before the end of the season is great for him in the sense of playing in the World Cup.

"It would be great to get him back and I wouldn't be against him playing in the World Cup because it would get him playing games again."

Heinze recently told the club's website: "I expect to play again in one month.

"The Argentina doctor, Donato Villani, has evaluated me and we are all optimistic. I have worked hard and the results have been very positive.

"I have a bet with Sir Alex Ferguson about returning to the field this season and I'm going to win it.