The midfielder played in Norway's opening Nations League against Austria, conceding a penalty in a 2-1 defeat. But he has been withdrawn from Monday's match against Northern Ireland.
The Blades have more time than most to prepare for the start of the 2020-21 campaign, with their match at home to Wolverhampton Wanderers kicking off on September 14.
Fellow midfielder John Fleck is away with Scotland, although Oliver Norwood, John Lundstram and Ben Osborn have been able to stay with the Blades as they work towards the opening game.
They are hopeful of adding to their squad this week, with owner Prince Abdullah bin Musa'ad telling TalkSport on Monday he was optimistic of “finishing” “two or three” signings before the end of the day. His club has been heavily linked with Derby County defenders Jayden Bogle and Max Lowe, as well as West Bromwich Albion striker Oliver Burke.
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