Arsenal vs AC Milan: 5 Keys to Round of 16 Champions League Duel

Arsenal and AC Milan headline the return of the Champions League in the round of 16 with a clash of elite footballing powers both starving for European cup success.

AC Milan has not been to the final of this competition since the 2007 season when they defeated Liverpool 1-0 to win the title, and Arsenal has never won the competition but last competed in the final in 2006 when they lost to Barcelona 2-1.

Milan leads Serie A with a two-point edge over Juventus but this is the competition they really want to win this season and haven't gotten past the quarterfinals since 2007.

Arsenal has not been past the quarterfinal since 2009 thanks to two defeats to Barcelona at this stage of the competition the last two years.

One of these clubs is going to exit the competition much earlier than they would have liked, so let's look at five keys to this awesome Champions League matchup.

Away Goals Will Be Massive

In the Champions League away goals are worth their weight in gold, because they are the tiebreaker in determining who progresses to the next round.

Arsenal manager Arsene Wenger has stressed the importance of getting an away goal on Wednesday in the first leg of this fixture at the Giuseppe Meazza.

Wenger said via Goal.com:

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"The European system is organised to reward audacious action away from home. "When you go away in the Champions League, you have to score. "The best way to score is play in an offensive way, and we will try to do that."

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Arsenal has played well at home this season and would be boosted tremendously by an away goal on Tuesday to turn the tie in their favor.

In the group stage, Arsenal scored five goals in five away matches and were defeated in only one of those clashes.

Milan's away record is good too, and they even scored two goals at the Nou Camp against Barcelona in the first group stage match of their European campaign. 

The Middle of the Defense Will Be Key

Arsenal has had troubles in the middle of their defense this season and have allowed too many goals late in matches that have cost them valuable points in the Premier League title race

Per Mertesacker has not played to his standards this season, and the Arsenal center backs as a unit must play better against a Milan attack that includes world-class forwards like Zlatan Ibrahimovic, Robinho and Alexandre Pato.

Milan's defense is solid in the middle, and Brazilian center back Thiago Silva may be the best central defender the Gunners face in any competition this season. He has tremendous pace for a defender and is strong enough to stop anyone who muscles with him.

Central defense is vitally important in this fixture.

If Robin Van Persie Is Defended Well, Can Arsenal Win?

While it would be unfair to say Arsenal cannot win if Milan shut down Dutch striker Robin van Persie, the chances the Gunners win without two solid performances from their star forward are quite small.

Van Persie leads the Premier League with 22 goals scored, but no one else on Arsenal has more than four goals in league play. 

Players like Andrey Arshavin, Theo Walcott, Alex Oxlade-Chamberlain and even Thierry Henry must step up for Arsenal if they are to progress to the quarterfinal without Van Persie dominating the attack.

Milan has to devote a lot of attention to Van Persie, and if they're successful in stopping him, they will likely reach the next round.

Thierry Henry Can Give Arsenal Emotional Boost with Solid Performance

Arsenal legend Thierry Henry has rejuvenated the club this season and has been hugely important in their FA Cup and Premier League success thus far, and Arsene Wenger confirmed Henry will be in the club's lineup for Wednesday's first leg in Milan.

Wenger said via Soccernet:

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"The players are happy that he is here. It is more to do with the interaction physically in everyday training. Of course, how much he wants it as well," he said.

"I was convinced quickly [that he was still capable of playing in the Premier League] but I wasn't sure that he would like the challenge. He knows that somewhere, people will look at how he is doing now."

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During Henry's two-month loan spell, he has scored several goals for the Gunners, but will have just one more opportunity to play hero, as he will return to the New York Red Bulls of the MLS after Wednesday's match when his loan ends.

Henry is a big-match player and has performed spectacularly in his Champions League career, and if he can score a crucial away goal for Arsenal on Wednesday, it will give the club a tremendous emotional boost.

Milan Must Play Much Better in England

AC Milan's last two Champions League campaigns have ended in England, and both times the second leg was played in England, with Milan scoring zero times.

A scoreless draw ended their European season last year when they were beaten 1-0 on aggregate by Tottenham in the round of 16, and they were beaten 4-0 at Old Trafford to Manchester United in the quarterfinal in 2010.

This year's second leg will also be in England, and Milan must find a way to score more goals in a country they haven't played well in recently.

Striker Zlatan Ibrahimovic was known for playing poorly in England before scoring two goals in the quarterfinals for Barcelona against Arsenal in 2010, but overall he has failed in England.

Milan will need an away goal to carry them through to the next round, which means they must play well at the Emirates in the second leg.