Maybe it shouldn't have been such a surprise that the team able to slow Arsenal's championship push would be captained by their former skipper, an ex-Gunner. The substitute Brobbey scored an stoppage-time equaliser after late goals from Saka and Trossard had put the visitors in the lead following a early goal from the home side captain Dan Ballard.
Proved to be a rocky night for the English top division pace-setters, but the Gunners have a seven point advantage over Manchester City, who host Liverpool on Sunday, and the hosts, though the Blues could reduce the gap to six points in the weekend's later game.
The Swiss international – who departed the Arsenal's home in last year seeking what he described as a fresh opportunity – has been exceptional in the promoted side's midfield this campaign after signing from the German club, but the veteran's performances on Sunderland's home turf will not have surprised Gunners fans. The Switzerland international revived his Gunners stint under Mikel Arteta, who was reluctant to lose him.
The Black Cats went into the game with no pressure after making the best start to a top-flight campaign by a newly promoted club over ten matches since Hull in the 2008/09 season. A redirected effort from the midfielder against the Toffees on Monday night had boosted Sunderland up to fourth place, a standing not many local fans would have envisaged before a ball was kicked given that their side had spent almost a decade outside the Premier League.
The player's experience, largely earned during his lengthy spell at Arsenal, and captaincy have assisted the squad rapidly adapt to Premier League football. He appeared to thrive in the physicality of the contest.
Arteta, again without Gabriel Jesus, Martin Ødegaard, Kai Havertz, Madueke, Viktor Gyökeres and Martinelli, had an early concern when Merino, leading the line after netting two goals in midweek's three-nil European win at Slavia Prague, was struck by an elbow from the defender as he challenged for a cross into the home box. Merino was fit to continue.
Eze almost cashed in of an error from Le Fée, who was dispossessed on the border of the penalty area, but the attempt soared over the bar.
Isidor shot wide at the opposite side before a further lengthy break after a clash of heads between Le Fée and Jurriën Timber, who had to continue with a bandaged head.
A tougher blow was to come next for stunned Arsenal. Sunderland sent a free-kick into the Arsenal area and Ballard held off Rice to lash the ball past David Raya after it was knocked out. It was the opening strike they had conceded since their last visit to the north-east in late September, when they had underlined their championship potential with a last-gasp win over the Magpies.
Arsenal had kept a club-record eight consecutive clean sheets in every match since Nick Woltemade's scored against them at St James' Park.
The Black Cats made sure that it was a further difficult outing to the region for Arsenal, who found themselves pegged back for periods after the break.
They needed a instance of quality, and it came in the 54th minute. The midfielder won possession off his opponent and a smooth attack featuring Eze and the striker culminated in the forward beating Robin Roefs at his near post.
Arsenal pushed for a second goal and Le Bris made a triple substitution to his offense – he brought on Brobbey, Chemsdine Talbi and Simon Adingra – midway through the final period.
Another example of skill was not long in coming. Arsenal worked the ball from one flank to the other, and the Belgian, just outside the box, found enough room to fire a right-foot shot into the top corner.
Raya had to be sharp in the last 10 minutes as the hosts pushed for a second goal, but could not stop an acrobatic shot from Brobbey after the ball was headed into the penalty area. The goal was met by a huge roar.
Appropriately Ballard – similar to his teammate a former Arsenal player, this one developed in Arsenal's academy – had the last word with a diving challenge at the toes of the attacker in the match's last action.