Arsenal capitalise on referee's error, advance to last eight of the Europa League

LONDON -- Three quick thoughts from the Emirates as Arsenal defeat AC Milan 3-1 on the night and 5-1 on aggregate to advance to the quarterfinals of the Europa League.

1. Arsenal see off Milan with a little help from the referee

Arsenal are back in a European quarter-final for the first time since 2010, though they needed a friendly refereeing decision to kill off AC Milan's attempt at a comeback.

Danny Welbeck ensured Arsenal's passage as he scored his first goal in more than two months after earning a penalty that was either a shameless dive or a comical stumbling over his own feet. Either way, it cancelled out a stunning opener from Hakan Calhanoglu scored just four minutes earlier which had suddenly made Arsenal's 2-0 lead from the first leg look in serious danger.

But Milan didn't have another reply and Granit Xhaka made matters safe in the second half before Welbeck added his second with a late header.

It means Arsene Wenger -- who has had his fair share to say about poor refereeing decisions this season -- can still dream of a first-ever European title, and the possibility of earning Champions League football next season.

Wenger's side have exited the Champions League's at the last-16 stage in each of the last seven years, and briefly looked in danger of reliving that fate in this second-tier competition as well.

After controlling the game comfortably for the opening 30 minutes, the Gunners were suddenly trailing as Calhanoglu found space more than 30 yards out from goal and unleashed a stellar strike that curled away from David Ospina and inside the far post.

But the lead didn't last long, thanks to referee Jonas Eriksson and some strange theatrics from Welbeck. The forward chased a ball from Mesut Ozil and fell down under a challenge from Ricardo Rodriguez, although replays showed there was no contact.

Welbeck took the penalty himself and calmly sent the goalkeeper the wrong way.

Milan were furious with Eriksson and only grew more so when appealing for their own penalty minutes later when the ball struck Calum Chambers' arm in the box. However, the Swedish referee waved that one away.

Patrick Cutrone missed Milan's best chance in the second half with a volley that went just wide before Xhaka killed off the tie in the 71st with a low strike that highly-rated teenager Gianluigi Donnarumma somehow pushed into his own net. That killed off any resistance from the Italians, and Welbeck added some late polish to the win by heading in a rebound from close range.

2. A brace and England call-up makes for a good day for Welbeck

If anyone needed to get on the scoresheet, it was Danny Welbeck. The Arsenal forward has looked almost painfully short of confidence in recent games, always toiling tiredlessly but getting precious little in return for his efforts.

But on the day he found out he's back in Gareth Southgate's England squad, he was finally back among the goals as well. Seeing him step up to the penalty spot was a nervy sight for those who have seen him struggle so badly with his finishing lately, but he was apparently Wenger's top choice in the absence of both Pierre-Emerick Aubameyang and Alexandre Lacazette. But the penalty was a well-taken one, giving him his first goal since a consolation strike in Arsenal's FA Cup loss to Nottingham Forest on Jan. 7.

His second goal was fairly routine but will serve as an additional confidence booster.

The diving controversy aside -- and to give Welbeck the benefit of the doubt, he has a habit of falling over haphazardly these days -- this may be a perfect platform for Welbeck to build on going forward. He'll still struggle to retain his place in this Europa League side once Lacazette is back from injury but there could be more opportunities in the Premier League going forward if Wenger continues to rotate for those games.

Welbeck hasn't been at his best this season but Southgate's call-up shows his World Cup dream is far from over. And it may have become more realistic tonight.

3. Surprisingly timid display from Milan

Milan will no doubt leave London fuming about the two penalty decisions that went against them in the first half, but they should also scold themselves for coming out so timidly at the Emirates.

Gennaro Gattuso had said before the match that his side had "nothing to lose" and could "play with a great deal of tranquillity" at the Emirates. Presumably he meant without nerves, but perhaps his players took him a bit too literally. Because it was a very tranquil approach from the Italians to open the game.

After an early warning shot just seconds into the game when Andre Silva was left free in the area to meet a cross and fire into the side netting, Milan looked content to sit back and bide their time, allowing Arsenal's midfield to dictate proceedings to their own liking.

That tactic of dropping back and waiting for counters has often been effective at the Emirates for smaller Premier League sides hoping to hold out for a draw, but it was surprising from a side needing to erase a two-goal deficit.

And if nothing else, the visitors should have taken Laurent Koscielny's early injury as a signal to push forward and test Arsenal's back four, which has a history of collapsing completely without the France defender in these types of games; remember Bayern Munich?

But Ospina didn't have a proper save to make for the opening 30 minutes as the Gunners looked in complete control. When Calhanoglu's goal came, it was like a bolt of lightning from a clear sky.

And when Welbeck's penalty came minutes later, it felt like the tie was out of reach again.

Just as for Arsenal, the Europa League represented a last chance for Milan to salvage their season after a disappointing league campaign. They simply didn't do enough to grab it in either of these two legs, though.