A month before Ricky Ponting [Images] arrives in India with his team for an ODI series, Zaheer Khan [Images] -- after his dazzling display in England [Images] -- has become a subject of research for the Australians, revealed their pace spearhead Brett Lee [Images].

The Australians will be in India for playing seven ODIs starting September 29 and Lee felt Zaheer would be a big threat to their aim of a series sweep.

"We have been watching him very closely and I must say that he has done amazingly well in England. In fact we are doing a bit of research on him," Lee, who is in Delhi, told reporters on Tuesday.

Zaheer won the Man of the Series award in the recently concluded Test series after picking up 18 wickets.

"I am very impressed with his determination. He has tremendous control over the ball and it looks he has worked very hard after being on the sidelines for some time.

"But ultimately it's all about putting the ball into the right areas and he has been doing it with consistency. Considering that he was not even in the team till some months ago, his comeback is just great."

Lee, who will return to the field in next month's Twenty20 World Championship after being sidelined by an ankle injury in February, said although the stars of the Indian team were now on the wrong side of 30's, they would still be a handful for the Aussies.

"I don't think that age would have any effect on the likes of (Sachin) Tendulkar, (Sourav) Ganguly, (Rahul) Dravid or VVS Laxman. These guys never let anything affect them when they are playing against us.