Arsenal's faint hopes of a top-four finish in the Premier League suffered another blow as John Fleck's late equaliser secured a valuable point for Sheffield United's own European ambitions in a 1-1 draw at the Emirates.
Gabriel Martinelli had filled the void left by the suspended Pierre-Emerick Aubameyang by opening the scoring for the Gunners on the stroke of halftime.
But Mikel Arteta's men were devoid of inspiration for most of the match and paid for one moment of poor defending as Fleck drove high past, Bernd Leno, eight minutes from time.
Arsenal have still lost just once in six games since Arteta took charge, but have won just one of five in the Premier League to remain 10 points off the top four in 10th.
"I'm very disappointed today," said Arteta. "It's two points dropped.
"In the Premier League, if you are 1-0 up in the last 10-15 minutes, you have to be careful because anything can happen."
The visitors remain four points ahead of the Gunners and move to within a point of the European places in seventh.
However, Chris Wilder did not hold back in his assessment of a sloppy performance from both sides.
"I didn't think it was a game of high quality. Nobody built up much momentum because both sides gave the ball away," said Wilder.
"I didn't think we were anywhere near our best today. The result is better than the performance."
A bright start by the Blades showed why they are surpassing all expectations on their return to the top flight.
However, their lack of a predatory finisher was shown as Lys Mousset twice headed over good chances in the first 10 minutes before Arsenal settled down.
Martinelli has made an impressive impact in his debut season in England and the 18-year-old was Arsenal's major threat in the absence of Aubameyang.
The Brazilian twice fired wide after being teed up by the impressive Nicolas Pepe but could not miss at the third time of asking seconds before halftime as Bukayo Saka's cross looped kindly into his path to tap home his ninth goal of the season.
"Gabi's gonna be a superstar," tweeted an impressed Aubameyang. "Not because of the goal, because of the attitude, energy and mindset."
Chances were few and far between after the break as Arsenal seemed to be keeping the visitors at bay bar a threat from set-pieces.
However, Sheffield United went nearly a year unbeaten away from home prior to visits to Manchester City and Liverpool over the festive period and showed the resilience on the road to claim a point seven minutes from time.
Arsenal did not deal with a deep cross into their box and it dropped to Fleck, who got over the ball to keep his strike on target and saw it fly hight past the helpless Leno.
"If you can get the result when you are not at your best it is a good quality," added Wilder.
"I don't know how much that was down to us, or not being put to bed by the opposition."
Wilder's men could even have taken all three points in the closing stages as Oli McBurnie and Fleck had shots bravely blocked inside the box a minute from time.