Jonathan Pearce
BBC Match of the Day commentator at Emirates Stadium

Ten of Jose Mourinho's squad will have missed a month of the campaign before its end. I can't think of another manager who could have rotated as well while keeping the club competitive for so long on four fronts.

But this could be too tough a task. Arsenal simply have to win to keep alive Champions League hopes. Arsene Wenger surely has to get a first ever league win against Mourinho.

Alexis Sanchez must improve on his record of just one goal in nine league games against the fives sides currently above Arsenal. But will United thwart them again?

BBC Radio 5 live

We've got full match commentary of this one - accessible via the link at the top of the page.

Tune in to BBC Radio 5 live's coverage for all the build-up now. Later you'll hear from Alan Green and Neil Lennon.

Striker Danny Welbeck leads the Arsenal line against his former club, as the Gunners keep their back three.

Wayne Rooney starts up front for Manchester United, who have Chris Smalling and Phil Jones back in the centre of defence. They are three of eight changes from Thursday's 1-0 win at Celta Vigo.

Full team news to follow.

Manchester United

Manchester United manager Jose Mourinho on which players he will rest against Arsenal: "The players that are in accumulation, the players that are with lots of minutes because we played nine matches in April and this one, so 10 matches in four-and-a-half weeks.

"The players that are in accumulation, they are not going to play at the weekend."

At least for Mourinho's men there is another way. Winning the Europa League this year plants them safely into next season's Champions League, regardless of league position.

But if they reach the Europa League final - in Stockholm on 24 May - it will be their 64th game of the season. And there are some tired bones already.

Chris Smalling, Phil Jones and Luke Shaw have been singled out for special mention.

And Ashley Young, Timothy Fosu-Mensah, Marcos Rojo and Zlatan Ibrahimovic are all injured too.

Image source, Getty Images

Of course, there are two sides to the heat going out of Mourinho and Wenger's so frequently unprofessional relationship.

That Mourinho has shied away from riling his rival might have a little something to do with his team's own league position.... 

The last time Arsenal and Manchester United both finished outside the top four was in 1978-79, when they ended seventh and ninth respectively.

Image source, .

Defeat today would be a serious blow for Arsenal's hopes of somehow sneaking back into the top four - like they always seem to do at this stage of the season. 

The Gunners have qualified for the Champions League for the past 20 years on the trot but this year?... 

Whichever side of the Wenger debate you fall - go, stay, maybe - the table doesn't lie. They are out in the cold.

Wind back a few years and the surround sound to this match would be brimming with broadsides. 

Jose Mourinho seemed to save his best jibes - or worst - for meetings with Arsene Wenger. 

But this week it's been all quiet on the build-up front. We were a long way from their most recent frothing-over - that touchline altercation at Stamford Bridge picture below - when Wenger said: 

"I am open always in life for everything, you know, for peace."

These days, he's got more to worry about from his own fans...

Image source, Getty Images

Mourinho on Wenger in 2005:

"I think he is one of these people who is a voyeur. He likes to watch other people.

"There are some guys who, when they are at home, have a big telescope to see what happens in other families. He speaks, speaks, speaks about Chelsea."

Mourinho on Wenger in 2014:

"Eight years without silverware, that's failure. He's a specialist in failure.

"If I do that in Chelsea, eight years, I leave and don't come back."  

Image source, Getty Images

We have had some classics. 

Image source, Getty Images

Like Thierry Henry's slick flick-up and volley over Fabien Barthez in 2000...    

Image source, Getty Images

Martin Keown losing it to the red mist of the Battle of Old Trafford in 2003...

Image source, Getty Images

Or that humdinger of a Champions League semi-final back in 2009 - Arsene Wenger's last sight of a European prize. 

But things aren't quite the way they were. You can't even rely on Jose Mourinho any more...