Doubles ace Mahesh Bhupathi feels lack of physical fitness was a major hurdle for junior Indian players in the way of international success.
"Our kids have talent but tennis has become a more physical game. They lack in physical fitness, therefore they find it tough while competing with western players," Bhupathi said on Wednesday.
"Physical fitness is the only difference, it is not about mental toughness. You are born with it (mental toughness), you cannot teach it," he added.
He cited the recent successs of Rohan Bopanna and Prakash Amritraj in the men's circuit.
On his chances of bagging the Rajiv Gandhi Khel Ratna Award this year, Bhupathi said, "I am looking forward to it."
The tennis ace was philosophical about his campaign at the Wimbledon not even taking off due to his partner's illness.
"Unfortunately he (Radek Stepanek) was sick. Cannot do much about it and we had to opt out."
When asked what made him believe that Sania Mirza could make it to the top-20 in women's tennis despite the fact that she has not performed exceedingly well at recent Grand Slams, he said age was at her side.
"I still stick to what I said earlier. She is talented and she is just 20 years old. I am sure with time she would improve," he said.