Borussia Dortmund's Niclas Fullkrug fired in a first-half goal to seal a 1-0 victory over visitors Paris St Germain in their Champions League semi-final first leg on Wednesday.
Nico Schlotterbeck floated a pass into Fullkrug's path and the Germany forward controlled the ball with a perfect first touch before drilling a low shot past keeper Gianluigi Donnarumma in the 36th minute.
PSG, fresh from being crowned Ligue 1 champions and desperate to win their first ever Champions League trophy, found it hard going against a disciplined German defence, especially in the first half with forward Kylian Mbappe largely neutralised.
The French side improved after the break and went agonisingly close to an equaliser in the 52nd with Mbappe curling a shot onto the far post and then Achraf Hakimi also hitting the woodwork on the rebound.
Only four minutes later Fabian Ruiz saw his stooping header sail wide after being left completely unmarked in the box before Dortmund keeper Gregor Kobel kept out Ousmane Dembele's close range effort in the 71st.
Dortmund, winners in 1997 and looking to reach their first final since 2013, soaked up the pressure as PSG's Vitinha narrowly missed the target 10 minutes later to leave the French side needing a win in Tuesday's return leg in Paris.
The winners of the tie will face either Bayern Munich or Real Madrid, who drew 2-2 in Tuesday's first leg in Munich.