England captain Harry Kane is set to have a scan on his right ankle on Wednesday, before Friday's World Cup group match against the United States.
He was eventually replaced by Callum Wilson and was later seen with light strapping on the ankle.
The 29-year-old Tottenham Hotspur striker was able to train on grass with the rest of the squad on Wednesday.
Manager Gareth Southgate will hope Kane's scan results are positive as he prepares his team for the second game of the group stage.
Midfielder James Maddison missed the Iran match as he recovers from a knee issue, while defender Harry Maguire came off feeling ill on Monday.