Arteta’s side fell behind to Ross Stewart’s first-half goal at a raucous St Mary’s before Viktor Gyokeres came off the bench to net the second-half equaliser.
Arsenal were well below their best in the absence of injured England stars Declan Rice and Bukayo Saka, while Brazil defender Gabriel Magalhaes limped off with a knee injury.
They were punished in the 85th minute when Shea Charles steered in Southampton’s winner from the edge of the area.
Arteta admitted he was disappointed with Arsenal’s lacklustre performance, with their sloppy defending especially frustrating.
“We conceded the first goal in a very unusual way for us, the second one was from direct play as well,” he said.
“We didn’t manage the long balls well enough. We just let the ball through us. Difficult to explain but credit to them.
“We had so much dominance in and around the box. We had two massive chances and needed to capitalise on that. But if you make defending errors we made today it’s very difficult to be in the semi-final.”
Arsenal’s hopes of a first FA Cup triumph since 2020 — their last major trophy — were blown away on the blustery south-coast.
The Premier League leaders have seen their quadruple and treble bids shattered by a 2-0 defeat against Manchester City in the League Cup final and now the limp loss to Southampton.
“You have to adapt to the wind, the injuries. You have to adapt to difficult situations in the season. Now we have to show what we are made of,” Arteta said.
Arteta had described the pain of losing the League Cup final as like “a ball of poison” in his stomach and Arsenal’s woeful FA Cup exit will surely leave the Spaniard reaching for the antacids.
Arsenal’s fifth defeat this term marked the first time they have lost successive games in all competitions in the current campaign.
They have little time to lick their wounds as they prepare for a Champions League quarter-final first-leg at Sporting Lisbon on Tuesday before resuming their charge towards a first Premier League title in 22 years.
The north Londoners are nine points clear of second-placed City in the title race. (AFP)
Edited by Tony Sabine
