Edoardo Bove's second-half goal gave Jose Mourinho's Roma the advantage over Bayer Leverkusen after the first leg of their Europa League semi-final.
The 20-year-old passed into the bottom corner after Tammy Abraham's shot was saved to score his first European goal.
Leverkusen's best chance saw Florian Wirtz drag wide in the sixth minute.
They had a chance to equalise in the 86th minute but Jeremie Frimpong's effort after a mistake by Rui Patricio was blocked.
Penalty appeals from the same incident were waved away by Premier League referee Michael Oliver.
However, Roma could have taken the lead before half-time but for an excellent save to keep out Roger Ibanez's header.
If they advance to the final, Mourinho would hope to maintain an outstanding record - he guided Roma to success in the Europa Conference League last season and has won his previous five European finals in charge of Porto, Real Madrid, Manchester United and Roma.
The game saw Mourinho up against his former player at Real Madrid in Xavi Alonso, with the Spaniard, now manager at Leverkusen, having previously played 151 games for the Portuguese manager over three seasons.
Source: BBC