United head coach Ruben Amorim confirmed Sesko suffered a knee injury after the £73.7million summer signing was forced off at the Tottenham Hotspur Stadium on Saturday.
Sesko came on as a substitute after 58 minutes but went down three minutes from time chasing down a long ball and it was immediately obvious he could not continue.
It was the latest setback for Sesko, who has endured a difficult start to life at Old Trafford.
But reports in Slovenia claim Sesko has already had initial tests on his knee and that they “indicate that the injury is not serious”.
Sportklub say the scans did not show a “worrying condition” but “only an MRI scan will show the full picture”.
The report says Manchester United “remain cautious for now” and that “the final diagnosis will be known after additional examinations”.
Slovenia are likely to provide an update on Sesko in the coming days ahead of their upcoming World Cup qualifiers against Kosovo and Sweden.
“I'm concerned with an injury, because it is in the knee and I don't know,” said Amorim. “We need Ben to be a better team. We have to check. He has something in his knee. Let's see.”