Terry Neill says Arsenal’s FA Cup quarter-final at Manchester United on Monday evening could be “a defining game” for both sides’ stuttering seasons.

The cup holders will travel to Old Trafford on Monday, roared on by their largest away following of the season – and knowing this is realistically their best chance of silverware.

On the other hand, defeat could seriously derail Arsenal’s campaign.

They trail Monaco 3-1 going into the second leg of their Champions League tie on the French Riviera and Arsene Wenger admitted recently that his side are not in the Premier League title race as they trail leaders Chelsea by nine points.

Neill – whose own defining moment came when he led Arsenal to a thrilling 3-2 win over United in the 1979 FA Cup final – recognises the importance of Monday’s clash.

The former Gunners boss declared: “Make no mistake, this has become a huge game for both sides. In fact this could very well be 90 minutes that defines both teams’ seasons.

“Both United and Arsenal have been inconsistent this season and it really is a game there for the taking – but it all depends on which team turns up on the night.

“United, of course, have the home advantage but we are now talking about a semi-final place being the prize and that should be a massive incentive for both sides.

“One thing I have noticed is that some bookies – and as we know, they rarely get it wrong – have edged Arsenal ahead as slight favourites. I also have a sneaky feeling for us but we have to be on our game.

“Yes, this isn’t the greatest United side ever – they are certainly not firing on all cylinders at the moment – but they are still very good and haven’t lost many.

“I believe we will need another great team performance – such as the one we produced at Manchester City – to win it. We have the talent and strength in the squad to get the victory we need.”

The Gunners have lost their last two FA Cup trips to Old Trafford; limping to a 2-0 loss four years ago this month while, back in February 2008, fans voiced their anger after a meek performance saw Arsenal lose 4-0 – one of the first times open dissent against Wenger was witnessed.

Indeed, Arsenal haven’t won at Manchester United in this competition since a controversial 2-0 win in 2003 – remembered more for a post-match altercation between Sir Alex Ferguson and David Beckham which left the England star nursing a swollen eye.

But both those most recent losses had one common denominator – Wayne Rooney scored.

The England talisman clearly loves playing against the Gunners and Neill has issued a word of warning.

“Wayne’s record is absolutely fantastic against Arsenal. Even when he was a teenager at Everton he scored a couple against us,” added Neill. “He is their key man and he could be a key influence in this match – history shows that is more than likely.

“Forget the big money he gets paid and all the trappings, the boy is a throwback. I love watching him because of it.

“There is still the kid playing in the street with his mates – he also had enormous desire and enthusiasm to go with that fantastic ability of his.

“He must be watched, he must be stopped because his record against us is both terrific and terrifying!”