MILAN --Ismael Bennacer gave AC Milan a 1-0 first-leg advantage in their Champions League quarterfinal against Napoli following a tough defensive battle against the Serie A leaders.

Bennacer's left-foot strike on 40 minutes was the difference between the two teams, but it was a costly night for Napoli who lost midfielder Andre-Frank Zambo Anguissa to a sending off in the second-half.

And with city rivals Internazionale winning their first-leg against Benfica in Lisbon on Tuesday, Milan kept alive the prospect of a Milan derby in the semifinals by sealing their win against Napoli.

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Rapid reaction

1. Milan gain crucial advantage as Napoli falter

AC Milan's hopes of an eighth Champions League title are still alive after Stefano Pioli's team withstood incessant Napoli pressure to seal a 1-0 first-leg quarterfinal victory at San Siro.

Despite being 22 points behind runaway leaders Napoli in Serie A, Milan will travel to the Stadio Diego Armando Maradona for next Tuesday's second-leg with a narrow advantage after Bennacer's 40th minute goal sealed their win.

But Napoli only have themselves to blame for the defeat. Head coach Luciano Spalletti's team dominated possession and missed a catalogue of chances, starting with Khvicha Kvaratskhelia's failure to score from three yards after just 52 seconds.

They also ended the game with ten men after midfielder Anguissa was sent off for two yellow cards. He will miss next week's second-leg through suspension, as will key defender Kim Min-Jae, whose booking in this game rules him out of the return fixture.

Milan owed their win to a series of top-class saves by goalkeeper Mike Maignan and the invention of midfielder Brahim Diaz, whose run from the centre-circle to the edge of the Napoli penalty area led to the only goal of the game. Diaz's pass to Rafael Leao was instantly played out to Bennacer, whose left-foot shot beat goalkeeper Alex Meret at the near post.

Eljif Elmas hit the crossbar for Napoli in the second-half and captain Giovanni Di Lorenzo also went close to scoring, but Spalletti's team couldn't find an equaliser.

But this tie is delicately poised and Napoli will still be favourites to go through due to home advantage next week. One thing for certain is that it will be a night to remember in Naples -- but for who is yet to be decided.

2. Napoli must gamble on Victor Osimhen in second leg

Spalletti said before this game that his team were capable of beating Milan without injured centre-forward Victor Osimhen, but after seeing the Serie A leaders miss a hatful of chances, it was clear that the Nigeria international's absence was painfully felt.

Osimhen has now missed three games with a groin injury since scoring twice in the 4-0 win against Torino in mid-March and Napoli have scored just two goals in those three games. Worryingly for Spalletti, two of those fixtures have been defeats against Milan -- 4-0 and 1-0 -- so the need for Osimhen to be involved in next Tuesday's second-leg is obvious.

The striker leads the Serie A scoring charts with 21 goals this season and he has also netted four in five games in the Champions League.

Spalletti left Osimhen out of this game on the basis that he didn't want to risk "losing him for five games" by playing him in this one. But Napoli's Champions League hopes now rest on the second-leg in Naples, so they need their top scorer back.

How fit he will be is another matter. Osimhen did not even travel to Milan for this game having missed training on Tuesday, so he may have to be patched up and perhaps only play for some of the second-leg rather than all of it. But by simply being in the squad next week, he will give Napoli a boost and also make Milan wary of his ability to be the decisive factor for Spalletti's team.

It's now all or nothing in the Champions League for Napoli, so expect Osimhen to play at least some part.

3. Milan prove that one-nation UCL ties are too close to call

When this quarterfinal tie was drawn last month, Napoli were overwhelming favourites due to being runaway leaders in Serie A. They went into this first-leg with a 16-point lead at the top and a 22-point gap between themselves and fourth-place Milan.

But the Champions League has a habit of springing surprises when domestic rivals meet in the knock-out stages to the extent that Milan always had a chance of defying league form to win this tie.

Valencia upset the odds back in 1999-2000 by defeating Barcelona in the semifinal to deny the Champions League a dream final of Barca against Real Madrid in Paris, while Wayne Bridge's winner for Chelsea against Arsenal in 2003-04 knocked out Arsene Wenger's great Gunners team -- they would become the Invincibles as unbeaten champions a month later -- out at the quarterfinal stage.

Jose Mourinho's Chelsea were beaten by Luis Garcia's so-called "ghost goal" in the 2004-05 semifinal by unfancied Liverpool, and Pep Guardiola's Manchester City have suffered quarterfinal exits against Liverpool and Tottenham when favourites to win in recent seasons.

Whether it is the pressure of being favourites or the fact that both sides start on a level footing, it is clearly tough to be the fancied team in a knockout tie between clubs from the same league.

But in this tie, there is also the undeniable weight of history in Milan's favour. With seven Champions League titles, they are a club that feels at ease at this level whereas Napoli have never been so far before.

Throw in the raucous backing of an incredibly passionate home crowd at San Siro and it is not difficult to see how Milan stepped up a level and Napoli struggled to match them.

Best and worst performers

BEST:

Mike Maignan, GK, Milan: Made some crucial saves for Milan to deny Napoli and ensure the Rossoneri go to Naples next week with strong hopes of reaching the semifinals.

Brahim Diaz, MF, Milan: Made the opening goal for Bennacer with a powerful run deep into Napoli territory. Milan needed a spark and he provided it.

Stanislav Lobotka, MF, Napoli: Such an efficient and clever player at the heart of Napoli's midfield. Always in control and rarely failed to pick out a team-mate.

WORST:

Piotr Zielinski, MF, Napoli: Lost the ball too often and his wastefulness gave Milan possession when the home side were being dominated by Napoli.

Alex Meret, GK, Napoli: The Napoli goalkeeper had a reasonably quiet night, but when he was called upon to keep out Bennacer's shot, he was beaten too easily at the near post by trying to save with his legs rather than his body.

Andre-Frank Zambo Anguissa, MF, Napoli: He had played well for Spalletti's team, but his sending off for two yellow cards in the closing stages left his team with ten men and he will now be suspended for the second-leg next week.

Highlights and notable moments

Despite Napoli being the better side, AC Milan converted one of their two shots on target to take the lead.

Ismaël Bennacer sends the San Siro into commotion!

A classic counter from Milan. ? pic.twitter.com/1yAH5vjONu

— CBS Sports Golazo ⚽️ (@CBSSportsGolazo) April 12, 2023

Another blow to Napoli in the form of a red card to Anguissa, who will miss the second leg.

André-Frank Zambo Anguissa is sent off after two yellow cards in just four minutes. ? ?

It gets worse for Napoli. pic.twitter.com/nnBxuJ8Wfd

— CBS Sports Golazo ⚽️ (@CBSSportsGolazo) April 12, 2023

After the match: What the players/managers said

Quotes to come...

Key stats (provided by ESPN Stats & Information research)

- Ismael Bennacer joins Yacine Brahimi, Nabil Bentaleb and Riyad Mahrez as the only Algerian scorers in UCL knockout stage history.

- Bennacer scores AC Milan's first quarterfinal UCL goal since Antonio Nocerino in 2011-12 vs Barcelona.

- AC Milan's 5 straight clean sheets are its longest a club record 7 consecutive shutouts between 2004-05.

- All 5 of Napoli's losses this season across all competitions have been via shutout.

Up next

AC Milan: Stefano Pioli's side will play Bologna in Serie A next on Saturday April 15 as they look to secure a top four finish, followed by the second leg of this fixture away in Naples.

Napoli: For head coach Luciano Spalletti and the Ciucciarelli the Serie A title is all but sealed as they host Verona next on April 15, and they'll turn their attention to continental success ahead of the clash with Milan.