AC Milan took a big step towards their first Champions League semifinal appearance for 16 years as Ismael Bennacer's goal secured a 1-0 win over Napoli in the quarterfinal first leg on Wednesday.
On a rainy night, Serie A leaders Napoli's first European clash with seven-time European champions Milan was also their first appearance in the quarterfinals of Europe's most prestigious club competition.
Attempting to avenge their 4-0 home defeat by Milan in Serie A this month, Napoli began pressing immediately.
Napoli had their first chance when the Milan defence failed to clear a low ball across the goal, but Khvicha Kvaratskhelia's attempt was blocked on the line.
Napoli midfielder Piotr Zielinski fired in a thunderous effort on goal, but Milan keeper Mike Maignan tipped it over the crossbar.
Milan's first opportunity came from striker Rafael Leao, who took the ball in his own half and made a solo run into the Napoli box before shooting just past the far post.
Although Napoli dominated most of the first half, the hosts took the lead five minutes before the interval when Brahim Diaz teed up Bennacer who struck a low shot inside the far post.
Milan had the opportunity to double their lead when a header from Simon Kjaer struck the crossbar and bounced down on the line, with the referee signalling that the ball did not cross the goal line.
Napoli's situation worsened 16 minutes from time when midfielder Andre-Frank Zambo Anguissa received a second yellow card for pushing Theo Hernandez.
Milan are the only team to beat Napoli more than once this season in all competitions ahead of the second leg of the quarterfinal on April 18.