Roma had just two shots on target with striker Romelu Lukaku cutting an isolated figure before being replaced after 80 minutes.

Substitute Tammy Abraham spurned a golden chance to reduce the arrears in stoppage time.

After an opening half hour short on quality, Leverkusen broke the deadlock when full-back Alex Grimaldo raced on to a misplaced backpass before setting up midfielder Wirtz for his 18th goal of the season.

Hosts Roma hit back with a flurry of chances but were unable to find a leveller before the interval.

Midfielder Andrich then doubled Leverkusen's lead midway through the second half, firing into the top-left corner from long range.

The victory stretched Xabi Alonso's side's unbeaten run to 47 matches in all competitions.

The other semi-final first leg between Marseille and Atalanta finished 1-1 at Stade Velodrome.

Forward Gianluca Scamacca put the visitors ahead after 11 minutes before defender Chancel Mbemba equalised with a long-range strike nine minutes later.

Both sides missed further chances, with the tie left in the balance before the second leg in Bergamo next week.