Hojlund had given his side a 10th-minute lead when he burst onto Marcus Rashford’s first-time pass, outmuscled young defender Ayden Heaven, then beat keeper Karl Hein with a shot through his legs.
The Dane turned a low Aaron Wan-Bissaka cross wide from close range before seeming to experience a muscle injury after 15 minutes that meant he could not continue.
Yoro’s exit was equally innocuous. The 18-year-old defender, who only joined United from Lille 10 days ago, went down and needed lengthy treatment, before he too called it a day.
Given the huge number of injuries that wrecked last season for manager Erik ten Hag, to lose two senior players in such a manner fewer than three weeks before United open their new Premier League campaign against Fulham at Old Trafford on 16 August is not ideal.
“We have to wait 24 hours and then we will hopefully know more,” Ten Hag told MUTV.
“We were very careful, especially with Leny. It is disappointing he had to come off but let’s be positive and see what comes out.”
Despite the bright start, the result was not to the Dutchman’s satisfaction either.
Gabriel Jesus levelled with a close range finish after 25 minutes, which Ten Hag was certain should have been disallowed for offside, before substitute Gabriel Martinelli cut inside 17-year-old rookie full-back James Scanlon to score the winner.
United did triumph in a pre-arranged penalty shoot-out that followed, with Jadon Sancho scoring the decisive spot-kick to seal a 4-3 win.