Former India coach Greg Chappell, in his new book Fierce Focus, claims batting maestro Sachin Tendulkar has occasionally been mentally fragile.Greg ChappellTendulkar is idolised by millions in India and the cricket world, and is considered the best batsman in the cricket history. But the Australian legend has revealed a different side of cricketer ahead of India's four-Test tour of Australia this summer, Herald Sun reported.At one point early in my time with the (Indian) team ... he came and talked to me for about two hours, Chappell wrote in the book.He was frustrated with his form and racked with self-doubt. Since he'd come back in Malaysia (in a one-day tournament in 2006), Sachin's mental state had been surprisingly fragile and he came to me for help.When the team travelled, he would snap on his headphones, not look sideways, and shut it all out. Not even Don Bradman carried expectations like this, and Sachin had been bearing it since 1989.He just couldn't get any rest. Once we were talking ... and I said, 'You must have so many friends, it must be hard finding time to keep in touch with all of them'. He looked me in the eye and said, 'Greg, you would have more friends in India than I've got', Chappell writes.