FULL-TIME
United 1 (Rooney 29") Arsenal 2 (Monreal 25" Welbeck 62")
93" Sanchez has a chance to wrap it up but is denied by De Gea who gets his fingertips in time push it out.
90" Five minutes of stoopage time added.
88" Arsenal aren't slowing the game down and that is helping United to go on the offensive.
87" YELLOW! Ramsey booked for tackle from behind on Young.
85" YELLOW! Januzaj booked for diving in the Arsenal box.
82" Man United have been hampered with a player short but their giving it their all. And Arsenal seem to be playing into their hands.
77" RED CARD! United down to 10 men after Di Maria gets his second yellow of the match. It seemed like he pulled referee Michael Oliver's shirt after first getting a yellow so the ref did the right thing to pull out the red card next.
73" What a fantastic save from De Gea, diving to save it with his left hand after Cazorla connected a cross which had goal written all over it.
72" Adnan Januzaj in for Rojo, while Giroud replaces Welbeck.
70" Sanchez free-kick is directed straight at De Gea.
67" The tall Fellaini goes for a Di Maria cross and beats a defender to a header but it lacks power and Szczesny collects.
66" Chambers replaces Ballerin.
65" Di Maria corner and Smalling taps over.
64" YELLOW! Rojo booked.
United 1 (Rooney 29") Arsenal 2 (Monreal 25" Welbeck 62")
62" GOAL! Poor feeble back pass from Valencia proves costly as Welbeck beats onrushing De Gea to the ball and finds an open net.
60" Di Maria beats the off-side trap, chests the ball down from Fellaini but misses the target..
58" YELLOW! Fellaini and Young booked.
54" Olivier Giroud is seen limbering up on the sidelines. His services are surely required as Arsenal look out of ideas upfront with Chamberlain too limping off.
52" Cazorla darts in dangerously then finds Sanchez who takes a shot with De Gea upfront but Valencia sticks his leg out and manages to deflect it.
49" Oxlade-Chamberlain limps off the field and in comes Aaron Ramsey.
47" Rooney is cramped for space in the box but manages two futile attempts.
United make two changes. Phil Jones and Michael Carrick are in for Luke Shaw and Ander Herrera.
The teams are out of the tunnel and ready for second-half action.
Half-time
United 1 (Rooney 29") Arsenal 1 (Monreal 25")
45" Fellaini's left-footer is collected well by Szczesny as he covers the ball with his full body. Two minutes added.
42" United are on the attack again. Di Maria this time goes for a shot but with his right foot and Szczesny does well to block it.
39" Superb stuff from United with Fellaini lobbing for Rooney who controls well on the run and crosses to Di Maria. The Argentine should have gone for a first-timer but instead he tried to trap and lost the ball in the box.
36" YELLOW! Herrera cautioned.
32" Di Maria has been sending some lovely floaters into the box and Szczesny so far has shown some butter fingers, fumbling with his collections.
31" De Gea makes a good save diving to his left after Welbeck leaps over two defenders to head goalwards.
United 1 (Rooney 29") Arsenal 1 (Monreal 25")
29" GOAL! Rooney heads home an inch-perfect cross from Di Maria.
United 0 Arsenal 1 (Monreal 25")
25" GOAL! The moment we have been waiting for. Nacho Monreal scores after Oxlade Chamberlain does the spadework by setting him up.
24" Even contest so far between these two sides. No quarter given nor asked for.
21" YELLOW! Marcos Rojo is booked for blocking Oxlade-Chamberlain.
20" Arsenal make a hash of a good counter-attack but Oxlade-Chamberlain shoots it across the goalmouth.
19" Good ball from Di Maria and Fellaini does well to chest-trap it in the box and back-pass it to Young but Young slams it over.
17" Ballerin overlaps as right defender and breaks his way into the United goal. His shot is however blocked by Smalling.
15" Both teams showing nerves in the first 15 minutes with wrong passes and poor shooting.
12" Rooney takes a free-kick which is timely punched away by Szczesny.
9" Arsenal get their first corner but Cazorla floats it in and the ball is cleared.
6" United earn a corner kick and Rooney dashes to the front post but his effort is misdirected.
3" YELLOW! Hector Ballerin gets an early booking for a rash tackle on Ashley Young and it's a free-kick just outside the box but Rooney's kick is headed to safety.
2" Arsenal step on the gas early with first Monreal making headway and then Sanchez entering the six-yard box. Luckily no danger to United's citadel.
Match gets underway.
Both teams are in the middle as the coaches take their respective places in the dugout. We are just a few minutes away from kick-off. Stay tuned.
It should be a cracking atmosphere tonight with 10,000 Arsenal fans packed in at Old Trafford as we are just 5 minutes away from kick-off.
Arsenal make five changes from the side which beat QPR as former United man Danny Welbeck starts up front while striker Olivier Giroud, who has scored seven and assisted four goals in his 11 FA Cup appearances for Arsenal, has to make do with a place on the bench.
Manchester United make one change from the side which beat Newcastle - Luke Shaw replaces the suspended Jonny Evans.
TEAMS
Manchester United XI: De Gea, Valencia, Smalling, Rojo, Shaw, Blind, Herrera, Di Maria, Fellaini, Young, Rooney. Subs: Da Silva, Jones, Mata, Falcao, Januzaj, Carrick, Valdes.
Arsenal XI: Szczesny, Bellerin, Mertesacker, Koscielny, Monreal, Coquelin, Cazorla, Oxlade-Chamberlain, Ozil, Sanchez, Welbeck. Subs: Gibbs, Giroud, Walcott, Ramsey, Chambers, Martinez, Akpom.
Fit again Aaron Ramsey will hope to return to the starting XI for Arsenal at the expense of Tomas Rosicky.
Olivier Giroud should continue to lead the line after his superb goal in midweek, meaning Danny Welbeck may have to make do with a place on the bench for his return to Old Trafford.
Elsewhere Falcao, Mata and Fellaini are likely to be vying for a starting berth in the Manchester United line-up.
Manchester United boss Louis van Gaal says a top four Premier League place is more important than winning the FA Cup. United are currently in fourth in the top flight - a point behind Arsenal - and haven't won the FA Cup since 2004.
Van Gaal said: "To finish in the first four is a fantastic result and for us at Manchester United even more I think.
"If you win the FA Cup you are not in the Champions League but you have won a title."
STAT ATTACK
Man United
Have won their last 6 home matches against Arsenal in all competitions.
Have been winning at both half time and full time in their last 5 home matches against Arsenal in all competitions.
Have won the FA Cup 11 times.
Arsenal
Have won four matches in a row in the league.
Have scored at least 2 goals in 8 of their last 9 matches in FA Cup.
Have won their last 3 matches in FA Cup.
Have won the FA Cup 11 times.
PROBABLE FORMATION
United: 4-2-3-1
Arsenal: 4-2-3-1
Wenger still haunted by Giggs wonder goal
Arsenal's FA Cup quarter-final at Manchester United on Monday will revive bitter memories for manager Arsene Wenger who says he is still spooked by a Ryan Giggs wonder goal in 1999.
Giggs scored one of the most memorable goals ever in the competition's long history when he weaved his way through Arsenal's defence in extra time to deliver a knockout blow in a semi-final replay at Villa Park.
Arsenal's Dennis Bergkamp had missed a penalty in the last minute of normal time with the score 1-1.
United went on to complete a treble but Wenger says that night at Villa Park proved pivotal and believes had Bergkamp not missed a penalty, United's run to glory would have been derailed.
"I saw the goal again when Giggs retired," Wenger said in an interview with The Sun. "It won them the treble because if Bergkamp had scored it was game over.
"It was a trauma for us in a negative way and for them in a positive way. It put them on the road to glory.
"I still can hear the shouts of that team having won (2-1). They couldn't believe it, because they were down to 10 men."
Back then Arsenal and United were the two dominant teams in England - vying for supremacy on an annual basis.
United ended up winning the Premier League in 1999 by a point from the Gunners and completed the treble with an extraordinary comeback against Bayern Munich at the Nou Camp.
"1999 was a miracle year for them," said Wenger, whose side beat United in the 2005 FA Cup final.
With United and Arsenal effectively out of the title race and in the bunch of clubs chasing a top-four finish, Monday's Cup tie offers a welcome distraction from worrying about points.
"The FA Cup is about giving it all on the day," said Wenger, whose side are third in the table, a point above United.
Champions League spot
The FA Cup could offer him a trophy in his first season in charge of Manchester United but Louis van Gaal says qualifying for next season's Champions League is the top priority.
United have not won the oldest cup competition in soccer since 2004 and host holders Arsenal in the quarter-final on Monday, hoping to move a step closer to ending their wait to lift the trophy for a record 12th time.
But Van Gaal's focus is on restoring United to Europe's elite club competition after the team missed out this season following their worst Premier League finish in the previous campaign when they were seventh.
The Dutch manager, who took over at Old Trafford in the aftermath of that calamitous season, says his side must treat the FA Cup as a mere bonus and concentrate on finishing in the Premier League's top four to secure a Champions League spot.
"I always want to get the goals what we have set. And the goals we have set is the top four," Van Gaal said.
"A title is fantastic. When you win the FA Cup you are not in the Champions League which is important for the club, but you have won a title. So for the players it is fantastic, for the manager it is fantastic but our goal is to reach in our first year together a place in the Champions League."
United are fourth in the league with 10 games remaining, 10 points adrift of leaders Chelsea and one behind Arsenal in third, whose own manager Arsene Wenger once said that the "first trophy is to finish in the top four."
And Van Gaal agrees: "I think that for a club the Champions League is the highest level and that's why he is saying that."
The Dutchman may have his sights set on European football ahead of hunting domestic silverware but he says it is still important for his side to beat Arsenal at Old Trafford, as it could affect their form for the rest of the league campaign.
"Every match you play has an influence in the next match. So we are in a 'rat race' in the Premier League and the club who wins the FA Cup match has a very good feeling for the next matches," Van Gaal explained.
"It could be damaging for the team that loses, but you can also react."