With questions now being raised about England's ability to chase down totals on difficult batting tracks, they are hoping that in-form batsman Roy regains full fitness soon as his replacement James Vince has failed to impress.
Roy has been crucial to England's white-ball success over the last few years.
He scored 153 runs in their World Cup game against Bangladesh, before pulling out due to a hamstring injury he picked up during the match against West Indies.
"Jason is making good progress from his hamstring injury. He is being assessed every day," an England and Wales Cricket Board spokesman said on Wednesday.
"Yesterday he batted in the nets and was running shuttles on the outfield. A decision on whether he'll be fit will be made when we train on Friday and Saturday."
Roy is not the only fitness concern for England, with bowlers Adil Rashid and Jofra Archer managing niggles.
Rashid has soreness to his right shoulder but is expected to be play on Sunday, while the England camp continues to monitor Archer's condition.
"Archer has tightness to his left side and will continue to be assessed ahead of the India match," the spokesman added.
(Reporting by Shubham Kalia in Bengaluru, editing by Pritha Sarkar)
