The Nigeria forward scored his 10th goal in his last eight appearances across all competitions, opening the scoring in the 40th minute after a period of concerted pressure from the visitors.

Osimhen had just hit the post and teammate Khvicha Kvaratskhelia had a penalty saved by Frankfurt captain Kevin Trapp as he faced deafening whistles from the home supporters.

Buoyed by Kvaratskhelia’s penalty miss, Frankfurt began pushing forward as the jubilant fans got louder and the game wilder.

Hirving Lozano capitalized on the extra space, racing down the right wing and crossing for Osimhen’s easy finish at the back post. They repeated the trick a minute later, but this time the goal was chalked out for offside.

Napoli captain Giovanni Di Lorenzo scored the second goal in the 65th by finishing a wonderful team move with a sweeping, curled shot inside the far post after Kvaratskhelia back-heeled the ball into his path. André-Frank Zambo Anguissa had played the Georgian in with a weighted through ball.

Frankfurt’s hopes of mounting a comeback were dealt a major blow minutes before when star forward Randal Kolo Muani was sent off for catching Anguissa with his open sole as both went for the ball. It means the French forward will be suspended for the second leg in Naples.

Frankfurt supporters set off a large pyrotechnic display behind one of the goals at the start of the game, partly in protest against local authorities after failing to reach agreement on a planned choreography due to safety concerns.

There was a heavy police presence at and around what was considered a high-risk game due to some of the supporters’ urge for violence. Police made nine arrests the night before and were prepared for more trouble later Tuesday.

Napoli’s supporters were shepherded to the stadium in an attempt to keep them away from the home fans, while there was also a large buffer area around their section in the stadium to ensure no contact between the rivals.

Napoli, which leads Serie A by 15 points, seemed rattled early on with uncharacteristic mistakes before Osimhen settled the visitors' nerves.

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