A game which descended into a farce at times saw four goals and three injuries. There were stray passes, defensive ineptitude, goalkeeping mishandling and two frustrated managers.
It was a night on which Manchester United arrived into a big game at Old Trafford with a host of injuries and one which Arsenal came out with similar issues. But neither side were rewarded for their physical struggles with the three points.
Shkodran Mustafi gave Unai Emery's visitors the lead after 26 minutes in a complete misjudgement from David de Gea.
Anthony Martial smashed home from close-range to level just five minutes later. The gap between two goals was even shorter in the second half as two horrendous defensive mistakes from each side saw Alexandre Lacazette put Arsenal in the lead before Jesse Lingard levelled 13 seconds later.
Arsenal's unbeaten run stretched to 20 games and they could have won at Old Trafford in the Premier League for the first time in over a decade. United were somewhat fortunate to get a win and are now four games without victory in the league.
Story of the game
De Gea's left boot would go on to prove vital for United, but he took until the 70th-minute mark to redeem himself. The first goal, after 26 minutes, was embarrassingly avoidable. Chris Smalling's lackadaisical marking allowed Mustafi a free header. Arsenal's German defender headed poorly towards goal but De Gea's parry was straight up in the air, and he couldn't react as it dipped down below his own crossbar.
Ander Herrera attempted to hook a foot up to meet it and did so, but not before the ball crossed the line. It would be the first of many diabolical defensive mistakes.
United's response, at least, was quick. But that it came from a set piece situation was indicative of their inability to create chances in open play with the absence of the benched Paul Pogba, who would come on with 15 minutes remaining.
Marcos Rojo's curled free-kick effort was met by Leno in the bottom right corner but a marginally offside Herrera reacted quickly to control the parry just before it crept off for a corner. He slashed it across the face of Leno's goal, where Lingard couldn't get a foot on it, but Martial could, smashing it in from close range to equalise less than five minutes after De Gea's error.
A one-minute spell much later demonstrated the immense ineptitude that these two sides can have in defence. Marcos Rojo's return from injury was marred by a flurry of mistakes.
First, the Argentine, who had not played since the World Cup, slipped the ball kindly into the feet of Henrikh Mkhitaryan, the former United man who had come on at half-time to replace an injured Aaron Ramsey.
Then, as Mkhitaryan played a one-two with Lacazette, Rojo aided the Arsenal cause further by diving at the feet of the latter and helping his shot sneak past De Gea.
'Anything you can do I can do better' must have been on Mustafi's mind. He had given Arsenal the lead. Rojo had responded with the great free-kick to set-up United's equaliser. Rojo showed how error-prone he can be, and Mustafi did, too.
13 seconds after the restart, Rojo's long ball had caused confusion in the Arsenal defence as substitute Lukaku failed to make an impact on it.
Mustafi headed it into the path of Lingard who tapped it between the legs of Leno to suddenly make it 2-2, out of nowhere.
The following 20 minutes descended into a display of why neither of these two sides should be considered on the level of the clubs considered to be their competitors.
Clearances sliced, players unmarked, passes astray; it was farcical at times.
Lacazette headed the ball out of De Gea's hands and stuck the ball in the back of the net, but that was deemed illegal. Mkhitaryan finished superbly from a rebound at a tight angle but was correctly ruled offside.
United, meanwhile, hardly looked to score. Aimless long balls were met by no one and Arsenal's pressure continued. Mourinho was furious on the touchline. Neither side deserved a point based on some of the woeful attributes they showed, and Mourinho's United drop even further away from the top four.