Rahul scored a fine half century in a tour match in Colombo, his first competitive game in close to three months due to an injury lay-off.
He is now down with fever and did not travel with the team from Colombo yesterday.
He also missed today's practise session here, making him a doubtful starter for the series opener.
If he misses out, Shikhar Dhawan and Abhinav Mukund are likely to open for India.
The team's other regular opener, Murali Vijay, too pulled out of the series at the last minute saying he had not fully recovered from a wrist injury.
"You know that you are physically fit and you have done everything that you can, worked really hard, you are feeling stronger, you are feeling fitter," Rahul told bcci.Tv.
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