Former power-hitting batsman Hayden says he saw it when he first started playing against the Indian veteran.
"I probably first heard Sachin's name in the early '90s. The one thing that always stuck in my mind about Sachin was that his size never ever matched his status," Hayden wrote in a book 'Sachin -- Cricketer of the Century' by Vimal Kumar, which will hit the stands in the first week of March.
"He was an incredibly slight man for someone who was such a huge brand within the game. It wasn't until I really played against him that I understood that there was a tiger that lay within him: he was a very competitive little man," he said.
Hayden also recalled an interesting incident from the 2008 Test series in India.
"My favourite Sachin moment was at the Mohali Test where he broke the world record for the most number of Test runs. There was so much excitement around the ground that the fireworks actually stopped play for the better part of 20 minutes, whilst the smoke cleared away," he recalled.
Writing in the same book, former Australian coach John Buchanan compared Tendulkar with Australian great Ricky Pontinh, who happened to be a contemporary of the Indian.
"Statistically, Tendulkar has a better record than Ricky Ponting. If Tendulkar is far more orthodox, far more classical and technical, Ricky is a little more unorthodox," he explained.
Buchanan, however, felt it was difficult to choose between Tendulkar and Ponting.
"Sachin definitely is a better player of spin bowling, more so on the challenging and spin-friendly wickets of the sub-continent," he said.
"I would have loved to see Ricky's domination over spinners in the same way as Sachin's, and vice versa, the Master's audacity on the front foot like the Tasmanian's against the best fast bowlers.
"Only if these two qualities were exchanged in their respective games could either of them have bettered Sir Bradman's Test average," he added.
Buchanan praised Tendulkar's mental toughness.
"Sachin has an exceptional ability to relax and can switch on and switch off with ease without any fuss. To get away from cricket and can come back recharged year after year for decades has been really marvellous. The Master has been the greatest exponents of doing that."