Arsenal missed the chance to regain their four-point lead at the Premier League summit after Stuart Armstrong's second-half equaliser held the Gunners to a 1-1 draw at Southampton.
The Gunners had enjoyed their best start to a top-flight campaign and dominated the first half on Sunday at St. Mary's Stadium, with Granit Xhaka opening the scoring.
Arsenal continued to look good value for their lead, with Gabriel Jesus spurning a couple of chances, but Southampton fought back as Armstrong levelled in the 65th minute.
Martin Odegaard saw a late strike ruled out as Arsenal moved two points clear of second-placed Manchester City, while Southampton extended their unbeaten run to three games and climbed into 15th.
Gavin Bazunu denied a fizzing Xhaka drive and Odegaard whipped narrowly wide, though Arsenal's early dominance soon paid dividends after 11 minutes.
Ben White overlapped down the right and clipped in a low centre for Xhaka, who expertly fired into the roof of the net.
Jesus almost doubled the lead but blasted just wide and should have sent Arsenal in two goals ahead at half-time when he volleyed straight at Bazunu one-on-one following a smart Xhaka throughball.
A last-ditch Mohamed Elyounoussi thwarted Jesus after the interval before the midfielder teed up Armstrong at the other end, with the Scotland international sliding past Aaron Ramsdale.
Odegaard thought he had grabbed a late winner, only for the assistant to flag for a goal-kick after Kieran Tierney failed to keep the ball in play in the build-up.
What does it mean? In-form Gunners falter
Arsenal's failure to grind out wins was a regular flaw in recent seasons, yet they went some way to easing those concerns with some resolute performances in the nine victories from their opening 10 league games.
Mikel Arteta's side appeared set to earn yet another narrow triumph, though an underwhelming second-half showing – coupled with a lack of clinical finishing – saw them drop points for just the second time this season.
With Chelsea to follow in November and City showing no signs of relenting in their title pursuit, Arteta will be frustrated to drop points at Southampton, who had lost seven of their last 11 Premier League home games.
Great Granit
Xhaka's impressive form for the Gunners continued as the Switzerland international scored his fourth goal in all competitions this season, matching his best return for Arsenal in a single campaign.
The Gunners have never lost in 18 games when Xhaka has scored (W15 D3), though Arsenal will be frustrated to not leave the south coast with victory here.
Jesus fails to deliver
Jesus has been a leading figure within a new-look Arsenal side, blending his hard-work ethic with an eye for goal up top, though the Brazil international failed to fire for the Gunners at Southampton.
The forward attempted a game-high four shots but only found the target with one of those, squandering presentable opportunities in either half in a disappointing showing.
What's next?
Arsenal head to PSV in the Europa League on Thursday before hosting Nottingham Forest on Sunday, while Southampton visit Crystal Palace the day before.