Lacazette's set-piece expertise ensures Gunners have little trouble in cruising into last-four date
Napoli 0 Arsenal 1 (Arsenal win 3-0 on aggregate)
Alexandre Lacazette scored the only goal of the game as Arsenal booked their place in the Europa League semi-finals with a clinical 1-0 win at Napoli.
Leading 2-0 from the first leg, Unai Emery's side reserved arguably their best performance of the season for their potentially daunting trip to the San Paolo.
Lacazette fired home a 25-yard free-kick in the 36th minute and, although Arkadiusz Milik had earlier had a goal ruled out for offside, the Gunners seldom looked troubled.
They will face Valencia, one of Emery's former sides, in the last four after they wrapped up victory in their all-Spanish clash with Villarreal.
Lacazette, who has now been involved in 25 goals for the Gunners this season, said: "I've been practising free-kicks in training.
"All my team-mates believe in me, so I'm happy to score tonight, and for them."
Defender Laurent Koscielny believes the important work was done in the first leg at the Emirates.
"We came here with ambition, we wanted to win, to score some goals, and we did that," said Koscielny.
"Napoli played in the Champions League this season so they are a good team, a good squad with good players. We did the job at home, keeping a clean sheet, scoring goals. We knew if we scored one tonight they would have to score four.
"After we went 1-0 in front we fought to defend, which is good for the spirit of the team. We kept a clean sheet which is important for confidence and for the rest of the season."
Arsenal's lead should have been doubled soon after the break, Henrikh Mkhitaryan - on for the injured Aaron Ramsey -playing in Pierre-Emerick Aubameyang, only for goalkeeper Alex Meret to make a superb stop to deny the Gabon striker.
Napoli were kept at arm's length by a determined Arsenal side, showing much more guile and threat than they mustered in beating Watford's 10-men 1-0 on Monday night.
There was an occasional threat to Arsenal's lead but Petr Cech's most difficult save came as a cross bounced off team-mate Nacho Monreal and had to be kept out.
Napoli: Meret, Maksimovic (Mertens, 46 mins), Chiriches, Koulibaly, Ghoulam (Rui, 71 mins), Callejon, Allan, Fabian, Zielinski, Milik, Insigne (Younes, 60 mins). Unused subs: Ospina, Malcuit, Verdi, Hysaj.
Arsenal: Cech, Papastathopoulos, Koscielny, Monreal, Maitland-Niles, Torreira, Xhaka (Elneny, 61 mins), Kolasinac, Ramsey (Mkhitaryan, 34 mins), Lacazette (Iwobi, 68 mins), Aubameyang. Unused subs: Leno, Ozil, Mustafi, Guendouzi.
Referee: Ovidiu Alin Hategan (Romania)
Man of the match: Alexandre Lacazette
Match rating: 6/10