At St Mary’s, Arsenal’s search for a response ended in another setback. Southampton beat the Premier League leaders 2-1 in the FA Cup quarterfinals, knocking them out and exposing a side that suddenly looks short on momentum at a crucial stage of the season.Just two weeks ago, Arsenal were being talked about as potential quadruple winners. That conversation has quickly faded. Defeats to Manchester City in the Carabao Cup final and now this FA Cup exit have brought them back to reality.The shift was even reflected off the pitch, with Southampton’s official X account responding to an Arsenal fan with, “Enjoy your quadruple, pal.”On the pitch, Arsenal had control of the ball but not of the game.Despite naming a strong side, they struggled to create clear chances and never fully dealt with Southampton’s direct approach.The hosts were sharper and more purposeful. Their plan to play early balls in behind the Arsenal defence repeatedly caused problems. It paid off in the 35th minute when Ben White misjudged James Bree’s cross, allowing Ross Stewart to control and finish past Kepa Arrizabalaga.Arsenal responded after the break but without real authority. They eventually found an equaliser in the 68th minute when Gabriel slipped Kai Havertz through, and the German squared for Viktor Gyokeres to finish.Even then, Southampton looked more dangerous. Tom Fellows and Leo Scienza both threatened before the decisive moment arrived. Fellows turned provider again, and substitute Shea Charles finished calmly to restore the lead and send the home crowd into celebration.From Arsenal’s perspective, this was a worrying performance. The intensity was missing, the defensive structure looked vulnerable, and injuries continue to disrupt rhythm. Gabriel Magalhaes going off added to the concern.Mikel Arteta spoke about the need for clarity, energy and belief, but the larger issue is timing. This is the phase of the season where small drops in level can have big consequences, and Arsenal have now suffered back-to-back defeats.For Southampton, this was fully deserved. They played with confidence, pressed well and attacked with intent. A place in the semifinals now awaits, keeping alive hopes of a memorable cup run.Arsenal must respond quickly. They remain in a strong position in the league, but with Manchester City closing in and a Champions League quarterfinal against Sporting next, the coming weeks could define their season.