Dhoni said at the customary pre-match press conference that he developed soreness on his back during the morning practice session at the Feroze Shah Kotla ground here.
He was actually asked about the absence of middle-order batsman Yuvraj Singh at the training session and the skipper said, "If at all somebody is doubtful, it's me. I have a sore back and we have called Dinesh Karthik as back up.
"Since it was an optional practice session, Yuvraj did not come," he said.
Asked, who will lead the side if he does not recover in time, Dhoni said, "Let's hope that I play. We'll see tomorrow."
The beleaguered Indian batting line-up could come under more pressure if Dhoni sits out tomorrow. He has been India's top scorer in the series with a 113 not out in the first match in Chennai and an unbeaten 54 in the second in Kolkata.
Asked if it would be a setback for Indian batting, which has been struggling to put up decent scores against Pakistan in the first two matches, Dhoni replied in the negative.
"Nobody is irreplaceable. I am sure if Dinesh plays tomorrow, he will bat as good as I batted in the last two games," he said.
With only pride at stake after losing the three-match ODI series against Pakistan, the Indian team underwent a rigorous training session here today ahead of the final match tomorrow with the spotlight on some under-performing players, including opener Virender Sehwag.
The full Indian squad, sans middle order batsman Yuvraj Singh, had a three-hour long training session under coach Duncan Fletcher at the Feroze Shah Kotla with under-fire opening duo of Sehwag and Gautam Gambhir having extended batting sessions.
Yuvraj was conspicuous by his absence in the practice session.
With the dense fog and bone-numbingly chill weather prevailing in the Capital, the Indian players arrived at the Kotla around 11:45 am. As soon as they came out at the ground, the sun smiled on them bringing a sense of relief to the players.
There was the customary game of football as some moved gingerly while others showed their ball-control skills. The short session set the stage for a gruelling fielding session followed by the nets.
The fielding session saw players having throw downs and slip catching practice in two batches, one led by coach Duncan Fletcher and other by fielding coach Trevor Penny.
While Sehwag, Rohit Sharma, Ajinkya Rahane, Ravindra Jadeja, Ashok Dinda and Dhoni were Penny's batch, the other group comprising Suresh Raina, Ajinkya Rahane, Virat Kohli, Gautam Gambhir, Ishant Sharma and Bhuvneshwar Kumar was closely observed by Fletcher as he was seen egging on the players to be accurate with their throws.
After the warm-up session, the batsmen hit the nets with renewed vigour and punished the local DDCA bowlers with their impressive shot selection.
The batsmen batted in pairs – Sehwag and Gambhir, Kohli and Rohit Sharma, Raina and Jadeja – with the Delhi opening duo, who face the net bowlers first, came back again after a half-an-hour stint.