Just before half-time, the striker went down after landing awkwardly. He received lengthy treatment and required an oxygen mask.
Dike, 22, was taken off the field on a stretcher, and West Brom manager Carlos Corberan fears he faces a long stint on the sideline.
"It looks like an Achilles injury, and they never really are good," he told Birmingham Live after the match. "Achilles injuries are never easy to manage, but still, we need to assess. But never, the Achilles injuries are good to manage."
Dike was not called up to the USMNT squad for the 2022 World Cup in Qatar after struggling with injuries.
The striker had put himself back into contention with the USMNT after scoring seven goals in 23 Championship matches for West Brom this season.
On Sunday, the U.S. announced that Paul Arriola and Cristian Roldan had been dropped from the roster put together for a Wednesday friendly against Mexico on Wednesday and that FC Dallas midfielder Paxton Pomykal had been added.
Dike was not part of that roster because the match fell outside of a FIFA international window and the team was almost entirely comprised of U.S. domestic players.