James Rodriguez departed Colombia's World Cup game against Senegal through injury, leaving his coach Jose Pekerman to say he is "very worried" about his star midfielder.
James was substituted after 30 minutes after the Bayern Munich man punched the turf in frustration before looking upset as he exited the game.
"I am very worried," Pekerman said after Colombia advanced to the round of 16 with a 1-0 win. "The situation is tough for the team, it is not an easy situation."
James did not start Colombia's opening game, a defeat to Japan, because of a calf injury and it appeared that may have resurfaced on Thursday.
"He trained normally up until yesterday and even yesterday he stayed after practice, as he always does, taking extra shots, free kicks, penalties," Pekerman said.
"He has been in optimum conditions for all the recent training sessions and at the last, we had no indication he was in any pain. Now, sincerely, I honestly don't know how he is."
Pekerman said he would await the results of medical tests to make a determination on whether James would be able to play against England in the round of 16.
"I don't have any confirmation of injury or any information at all," he said. "We must wait. We are hoping that it will be good news after the medical tests and then we will know for sure what has happened."
Before leaving the game, James put in a frustrating performance in which he completed only two of 10 passes attempted.
The 26-year-old won the Golden Boot at the 2014 World Cup and this latest setback came four years ago to the day since his wonder strike against Uruguay earned him the Puskas award for best goal of that year.
Colombia will miss Rodriguez's creativity and ability on the ball if he misses their last-16 encounter after they laboured to breakdown Senegal before Yerry Mina's bullet header in the 74th minute sealed a dramatic win.
The result sent Colombia through as Group H winners while Senegal missed out on the knockouts by virtue of having a worse disciplinary record than rivals Japan. It was the first time in World Cup history that a team had been eliminated from the tournament because of the amount of yellow cards they had accrued.
Pekerman acknowledged that it was a cruel way to exit the World Cup but no worse than losing on a penalty shootout.
"We all knew when we came to the World Cup that these were the rules. It was incredible to be in this situation and hard for a team to take on," he said. "Had we been in their shoes we would have been disappointed.
"It happens to anybody -- in a final or semifinal. Sometimes, a World Cup final is decided on penalties. It is extremely hard."
Information from Reuters was used in this report.