Borussia Dortmund needs to beat Marseille to be sure of advancing from Group F of the Champions League.

A draw would be enough if Napoli fails to win at home against group leader Arsenal.

Dortmund can even afford to lose — if Napoli does the same.

Three teams could finish with 12 points — meaning that for the first time a side with 12 points would be eliminated.

Here are five things to know ahead of Wednesday's matches:

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MORE INJURIES

Borussia Dortmund has more injury problems with nearly every match.

The 1-0 loss to Bayer Leverkusen was made worse by the injuries to Sven Bender and Nuri Sahin, both of whom sustained right-ankle injuries. Bender has been ruled out of the match in Marseille and Sahin is highly doubtful.

"We want to spend the winter in the Champions League and that's how we'll approach the match. We are not going to lament," Dortmund coach Juergen Klopp said.

Neven Subotic, Mats Hummels, Marcel Schmelzer, Ilkay Gundogan and Bender are all out and defender Manuel Friedrich is ineligible for the Champions League.

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HELP PLEASE

Napoli desperately needs some help from Marseille if it wants to advance.

The Italian club can take matters into its own hands if it beats Arsenal by three goals, but that seems unlikely against the Premier League leaders. Otherwise, Napoli needs to beat Arsenal by a smaller margin and hope Marseille holds Dortmund to at least a draw, or draw with Arsenal and hope Marseille wins.

"We have the advantage of playing at home and we need to perform at our maximum," Napoli fullback Christian Maggio said. "Of course we'll wait to see how it goes in Marseille but first of all we've got to worry about ourselves."

Making matters more difficult for Napoli is that captain Marek Hamsik is out with a bruised foot.

Napoli fans have been warned to behave properly because UEFA has placed the club under probation for fireworks use and the next violation could result in a stadium ban.

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INFAMOUS FIRST

No French club has ever finished the group stage of the Champions League with zero points. Marseille could become the first one to achieve that unenviable feat if it loses to Dortmund.

Marseille has nothing to play for but pride. Beating last season's runner-up will be a tough mission though. Marseille will miss France playmaker Mathieu Valbuena and Ghana winger Andre Ayew through injury as well as Cameroon defender Nicolas Nkoulou and Togo midfielder Alaixys Romao through suspension.

The 1993 European champions did not have the best preparation for Wednesday's match. They lost to Nantes 1-0 in the French league on Friday. The club's poor run of form led to coach Elie Baup's dismissal the following day.

"I hope this loss will open our eyes," Marseille defender Souleymane Diawara said Friday, "because if we continue that way, we are going to crash into the wall."

Sporting director Jose Anigo has taken on coaching duties until the winter break.

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GROUP WIN

Already assured of advancing in the Champions League, Arsenal is also in the ascendancy domestically, leading the Premier League by five points despite being held to a 1-1 draw by Everton on Sunday.

"When we play to our peak, I think we can beat anyone so it is important that we go and do that on Wednesday," Arsenal defender Carl Jenkinson said. "It is going to be a tough game. They are going to be battling because they want to qualify just as much as us.

"But we will work hard and go out there with the confidence that we have from our recent results and hopefully come back with the result we want."

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LOOKING FOR LEWANDOWSKI

Robert Lewandowski has scored only three goals so far in this campaign, but two came in Dortmund's 3-0 home win over Marseille.

Lewandowski is one of the few healthy players from the Dortmund side that lost twice to Marseille in the 2011-12 group stage.

"It's a decisive game but we are going to make it," Lewandowski said.

Lewandowski leads the Bundesliga with 11 goals but he has underperformed in the Champions League and Dortmund will need his goals to advance.

Lewandowski is widely expected to leave Dortmund at the end of the season, with most reports linking him with Bayern Munich.