Premier League leaders Arsenal dropped points for only the second time this season after Southampton hit back to snatch a 1-1 draw at St Mary’s.
Granit Xhaka’s second goal in four days following his Europa League winner against PSV Eindhoven set the in-form Gunners on course for a 10th win from 11 top-flight games.
Yet Mikel Arteta’s men were left frustrated after Saints improved in the second period and equalised 25 minutes from time thanks to Stuart Armstrong’s first club goal since March.
Arsenal thought they had claimed a 79th-minute winner through captain Martin Odegaard but the ball was adjudged to have gone out of play before it was cut back by substitute Kieran Tierney.
The draw was Arsenal’s first in 32 fixtures in all competitions, dating back to a goalless stalemate with Burnley in January, leaving them just two points above Manchester City and with plenty of regrets.
Gabriel Jesus spurned two chances to stretch the visitors’ lead following Xhaka’s 11th-minute opener, while Gunners technical coach Nicolas Jover was booked for touchline protestations shortly after Armstrong’s leveller.
Arsenal’s last visit to St Mary’s – a 1-0 loss – was the third of three successive damaging defeats in April which ultimately cost them Champions League qualification.
The Gunners travelled to the south coast on this occasion as the top-flight’s early pacesetters, albeit their advantage had temporarily been cut to a single point by champions City’s 3-1 win over Brighton on Saturday, and with progression from the Europa League group stage already assured.
Arteta’s men wasted little time in asserting their authority on the contest.
Xhaka had already tested Saints goalkeeper Gavin Bazunu during a dominant opening spell when he emphatically thumped a right-footed half-volley into the roof of the net from level with the penalty spot after the rampaging Ben White played a one-two with Bukayo Saka and crossed from the right.
Southampton had ended a five-game winless run with a nervy 1-0 midweek victory at neighbours Bournemouth.
Yet, with Che Adams – their matchwinner at Vitality Stadium – beginning on the bench due to a hamstring concern, they initially lacked attacking threat.
Jesus almost doubled Arsenal’s lead just before the break but his volley following neat interplay with Odegaard was pushed away by Bazunu.
Elyounoussi then made another telling impact on the game as Saints levelled with their first meaningful attempt.
The Norway winger burst forward before delivering a perfectly-weighted through ball for recalled Scotland international Armstrong to calmly slip the ball beyond Aaron Ramsdale and into the bottom left corner.
Aside from the brief joy of Odegaard’s disallowed effort, Arsenal rarely threatened to regain the lead as their title aspirations suffered a setback.
Southampton, meanwhile, stretched their unbeaten streak to three games to further ease the pressure on under-fire boss Ralph Hasenhuttl.