Henrikh Mkhitaryan's first Arsenal goal helped put the Gunners in control of their Europa League last-16 tie with AC Milan .
The forward and Aaron Ramsey struck to earn Arsenal , who need to win the European competition to avoid ending the season empty-handed, a 2-0 victory at San Siro.
It briefly eased the growing pressure on boss Arsene Wenger , under fire for their poor domestic season.
Arsenal host Milan in next week's second leg and they started brightly, with Mkhitaryan opening the scoring when he collected Mesut Ozil's pass on the left.
The Armenian also hit the crossbar in first-half stoppage time before Ramsey made it 2-0 when he latched onto a fine ball from Ozil to round Gianluigi Donnarumma and net.
Milan had been unbeaten in their previous 12 games and had not conceded in their last six matches.
Elsewhere, Saul Niguez's stunning solo strike inspired Atletico Madrid to a deserved 3-0 win against Lokomotiv Moscow.
The midfielder opened the scoring to set the two-time Europa League winners on course for the quarter-finals.
His effort came after he rode a challenge near the halfway line before advancing and, as the Moscow defence backed off, unleashing an unstoppable effort which darted into the top corner.
Diego Costa then added a second two minutes after the break and Koke bagged a late third with Atletico in control.
Valon Berisha's double earned Red Bull Salzburg a 2-1 win at Bundesliga giants Borussia Dortmund .
The midfielder scored twice for the Austrians in the second half, his first a penalty, but Andre Schurrle pulled a goal back to keep the tie alive for Dortmund.
In Russia, Lyon grabbed a slender 1-0 first-leg lead against CSKA Moscow thanks to Marcelo's second-half goal.
Lucas Ocampos scored after just 41 seconds as Marseille beat Athletic Bilbao 3-1 in France.
The ex-Monaco winger also netted in the second half as Marseille put one foot into the quarter-finals.
Former West Ham forward Dimitri Payet made it 2-0 after 14 minutes but Aritz Aduriz reduced the deficit from the spot after Adil Rami handled in the area.
Payet then laid on the third goal for Ocampos in the 58th minute.
Fredy Montero netted twice for Sporting as they beat Viktoria Plzen 2-0 in Portugal.
The striker grabbed the opener in first-half injury time and added a second just four minutes after the break for a healthy lead.
Junior Moraes and Viktor Tsygankov gave Dynamo Kiev a 2-2 draw at Lazio .
Ciro Immobile and Felipe Anderson scored quickfire replies after Tsygankov's opener at the Stadio Olimpico but Moraes levelled to set up an intriguing second leg.
Bruma and Timo Werner put RB Leipzig close to the last eight after a 2-1 win over Zenit St Petersburg.
The pair scored in the second half but defender Domenico Criscito netted a vital away goal with four minutes left.