With his stiff back improving substantially, Sachin Tendulkar today had a long session at the nets, as Indian team physio Andrew Leipus asserted that the batsman would be fully fit well in time for the first one-dayer against Pakistan at Karachi on March 13.‘‘He is much better now. His affliction was minor, and he’ll be fully fit before the Karachi game,” Leipus told newspersons here.Indian skipper Saurav Ganguly also corroborated Leipus. ‘‘He’s now OK. A stiff back is just like a stiff neck. It is not an injury’’, Ganguly said.Tendulkar was distinctly uncomfortable on Sunday and yesterday — the first two days of the conditioning camp at the Eden Gardens.He had skipped batting at the nets and confined himself to a fitness routine at the indoor gymnasium in the Eden Gardens yesterday before doing some physical exercises on the ground.He then put up a dismal show with the bat during a practic match, being dismissed three times in succession on miserly scores of 0, 0 and 4.He also did not come in to field for his side India A in the afternoon session on the same day.Tendulkar has been undergoing physiotherapy under the guidance of the physio and has been advised to take massage and follow an exercise regime, including long sessions with the Swiss Ball.