Colombia trained on Friday without the injured James Rodriguez as they began preparations for the round-of-16 World Cup clash against England on Tuesday.
James, who left Thursday's 1-0 win over Senegal after 30 minutes with muscle pain in his left calf, did not participate in the light training session, nor did Abel Aguilar.
The Colombia federation issued no official statement about the Bayern Munich player's status, but sources close to the team's medical staff said they would not receive the results of an MRI scan until Saturday.
The scan was carried out to determine the seriousness of the injury to an area of the calf that has bothered James for several months and caused him to miss their opening game of the tournament.
At his postmatch news conference on Thursday, Colombia manager Jose Pekerman said he was "very worried" about his star midfielder.
After being substituted for Luis Fernando Muriel, James was seen punching the turf in frustration before looking upset as he went straight to the dressing room.
"The situation is tough for the team -- it is not an easy situation," Pekerman said after the game. "He trained normally up until yesterday and even yesterday he stayed after practice, as he always does, taking extra shots, free kicks, penalties.
"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 the tests before determining whether James could play against England.
The 26-year-old won the Golden Boot at the 2014 World Cup, and his 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 James' creativity and ability on the ball if he does not play after they laboured to break down Senegal before Yerry Mina's 74th-minute header sealed the win.
Information from Reuters was used in this report.