Flintoff was forced off the field during Friday's win over Ireland in Guyana for treatment on his left ankle.
"I don't see it as a grave problem," England coach Duncan Fletcher told reporters when asked about the ankle, which the 29-year-old has had surgery on twice in the past.
He batted and bowled during practice at the Antigua Recreation Ground and is now expected to face Sri Lanka at the Sir Vivian Richards Stadium, the island's new home for international cricket.
Flintoff has endured a troubled World Cup, being stripped of the vice captaincy and banned for the Canada group game because of a drinking session and then recovering from a stomach bug to face Ireland.
England need to win at least one of their two matches against Sri Lanka and Australia (they play the world champions here on Sunday) to have a realistic chance of reaching the semi-finals for the first time since 1992.