Jesse Lingard cancelled out a spectacular opening goal from Philipp Wiesinger at Old Trafford before substitute Anthony Martial sealed the win with two minutes of normal time left. 

The first-leg thrashing in Austria, United's last game before the coronavirus pandemic halted the season, set the Red Devils up for a relatively comfortable return game against a side whose domestic season finished a month ago. 

Ole Gunnar Solskjaer made nine changes from the team that ended the Premier League season with a 2-0 win at Leicester City, leading to a disjointed first-half display in which it failed to muster a shot on target. 

Andres Andrade nodded the ball off the crossbar and Marko Raguz was denied by a good Sergio Romero save, as LASK showed greater early initiative.

United's first meaningful effort on goal was a low strike from Odion Ighalo, who turned well from Juan Mata's pass but shot too close to Alexander Schlager. 

At the other end, Romero could do nothing to stop Wiesinger putting LASK ahead, the defender sending a stunning first-time strike into the top-right corner from 25 yards out. 

The lead lasted just two minutes, though, Mata sending a pass into the path of Lingard, who had plenty of time to side-foot past Schlager from inside the penalty area. 

Romero just about kept out a Dominik Reiter effort at his near post before Solskjaer handed 18-year-old Teden Mengi his senior debut at right-back. 

It was another second-half substitute, Martial, who got the winner, combining superbly with Mata before side-footing through the legs of Schlager, who was just unable to keep the shot out.