Arsenal bounced back from a miserable fortnight to take a big step towards a Europa League quarter-final place with a 2-0 victory over Milan.
Henrikh Mkhitaryan's deflected strike put the Gunners ahead and their advantage was doubled when Aaron Ramsey rounded the goalkeeper before tapping in on the stroke of half-time.
Mesut Ozil set up both strikes, with Armenian forward Mkhitaryan tucking away the German's pass in the 15th minute before Ramsey put the seal on a fine move as he danced round Gianluigi Donnarumma.
Milan's Giacomo Bonaventura was a persistent danger early in the second half as Arsenal weathered the storm, but as the hosts ran out of ideas it was in the end a convincing victory for the much-maligned Premier League side.
Arsenal's best and perhaps only hope of Champions League football next season is via the Europa League and they have one foot in the last eight with a 2-0 lead to take back to north London, a result which ends a run of four consecutive defeats.
Ramsey told BT Sport 2: "We started well. We showed that we have plenty of characters in this team. It is never easy to come to San Siro and play AC Milan. I know from past experience - we came here and lost 4-0. I'm really pleased to win tonight.
"I thought we played very well in the first half, we created many opportunities, we moved the ball well and kept a clean sheet which is important. So all in all a good night's work.
"We've been on a bad run and sometimes as hard as you try on the pitch, it doesn't seem to work. We tried to do the right things, we know what we are capable of doing in the dressing room.
"A lot of people are always going to talk. It's important for us to always keep focused, try and improve. We know what we are capable of doing, we just have to try and produce that more consistently. It's nice to turn a corner and come here and get a good result."
More Europa League news
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.
Also in Thursday's early games, Lyon earned a 1-0 victory at CSKA while Dortmund were beaten 2-1 at home by Red Bull Salzburg.
Later on, 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.
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.
Wenger hails Arsenal desire
Arsene Wenger compared Arsenal's recent bad form to a "half knocked-down" boxer and was pleased with his side's response to their run of four successive losses.
He said: "It has been a nightmare week but it was a good result but it is not qualification, so we have to finish the job at home.
"Overall, I am happy with our spirit and the response we gave. We defended with resilience and until the end. We did that well tonight.
"(In the second half) our pace dropped but I think it is down to the fact we've played four games in 10 days - four intense games.
"I think that when we play a cup final on Sunday and you lose it, it is hard psychologically to digest that in three or four days and we had games on the bounce straight away. Like a boxing match, when you are half knocked-down and another (punch) comes again, and that's what happened to us.
"But at some stage, you have to respond with your pride and your desire that you have to quality to win the game and that's what we did."