Captain Nemanja Vidic and defender Jonny Evans could hand Manchester United a double injury boost by returning to full fitness in time for the start of the season.
Vidic believes he is on course for the Premier League opener against Everton at Goodison Park on August 20, after making his first appearance for eight months in Saturday's 0-0 draw against Valerenga.
The Serbia centre-back had been sidelined since December after injuring cruciate knee ligaments during United's Champions League exit to Basel.
Now his comeback will continue on Wednesday when United travel to Sweden to face Barcelona, who defeated them in the 2009 and 2011 Champions League finals.
"For me, it was really good to have 60 minutes in Oslo," Vidic told the club's official website. "Hopefully I'll play even longer against Barcelona and I should be fit for the beginning of the season."
Northern Ireland international Evans was expected to miss the beginning of the campaign after having surgery on an injured ankle, which ruled him out of the final three games of last season.
However, he could be in contention for the trip to Everton, with assistant manager Mike Phelan saying: "We hope he'll be available for the start of the season. He won't have had the games under the belt but, if he's fit and progressing well, we'll push him forward."
United are definitely without one central defender, with Chris Smalling sidelined for ten weeks because of a metatarsal injury, while Phil Jones left the club's pre-season tour of Scandinavia feeling unwell.
"At the moment, Chris Smalling is going to be a bit longer in his recovery," Phelan said. "He's had a setback, an injury, and he's progressing slowly."