A "tennis elbow" problem has already forced Tendulkar to miss three successive One-day events, starting with last month's Dutch triangular and including the ongoing Champions Trophy in England.
He now has only a few weeks to get fit for the first of four Tests against Australia, starting at Bangalore on October 6.
Tendulkar, who is currently undergoing treatment in London for the left elbow injury, has already been excluded by his state team Mumbai for the five-day Irani Cup match between the Ranji Trophy champions and the Rest of India starting in Mohali on September 22.
The only other first-class match before the Test series is the three-day game between a Board President's XI and Australia at Hyderabad commencing September 30.
But Leipus said at Edgbaston, where India were training in the indoor nets ahead of Sunday's Champions Trophy clash here against Pakistan, that Tendulkar was making progress.
"I spoke to him this (Tuesday) morning. He's still in London receiving specialist treatment. He's feeling greater strength in the elbow but there's still a bit of discomfort."
Leipus, describing the treatment, said: "In basic language it is like a shock treatment, an ultra-sound shock treatment where a large ultra-sound force has gone through the tissues, shakes things up and stimulates the healing process. At the same time he is getting much needed rest.
"He's got one more treatment left and then he'll make his way back to Bombay," explained Leipus who said he had consulted fellow Australian Chris Bradshaw, the doctor of London-based Premiership football side Fulham.
He added Tendulkar had been on track before suffering a setback in the Netherlands. "For the first couple of days we kept him away from the nets and did a lot of physiotheraphy. He then spent 10 minutes with the spinners and it felt good.
"But the first delivery against the quicks was a short ball and he played it with the top-hand only and I think that overloaded the complex. We've been struggling to get him back since then.
"The bowler was Ajit Agarkar. But they are still good friends!"
Looking ahead, Leipus said: "We expect to see him (Tendulkar) grabbing a bat again in another 10 days or so.
"There is a side game with the Aussies (the Board President's XI match). If he's up for it he will participate but if we think he needs a little more time with his re-hab we'll hold him back."
And he warned that the injury was something Tendulkar, 31, would have to guard against for the rest of his career.
"The tissues are never going to be as strong as they were the first time. But as long as we keep the elbow strong, and monitor his work load accordingly, we shouldn't make the same mistake again."
Leipus said that even if Tendulkar missed the Board President's XI game he could play in the first Test.
"He's the best judge if he has had enough practice. But he has told us he needs to be able to face 300 balls a day minimum quite comfortably before he will declare himself fit again."
Tendulkar's absence, even for a match, would be a blow to India who are aiming to win their third consecutive home series against Australia after 2-1 successes in 1998 and 2001.
In seven home Tests against Australia, Tendulkar has scored a mammoth 760 runs at an average of 63 and overall he is the fifth highest scorer in Test cricket with 9,470 runs in 114 matches at 57.39.
Tendulkar, who made his Test debut in 1989, has missed only one Test series in his 15-year career when a leg injury forced him to sit out the Sri Lanka tour in 2001.
After Bangalore, the remaining three Tests will be played in Chennai (October 14-18), Nagpur (October 26-30) and Mumbai (November 3-7).