Southampton captain James Ward-Prowse admitted it was a 'massive blow' after twice letting slip a two-goal lead against Arsenal.
The Saints were denied precious three points in their fight for survival by Bukayo Saka's last-minute equaliser in a thrilling 3-3 draw.
Saints had looked on course for a shock win to move off the bottom of the table after Carlos Alcaraz opened the scoring inside a minute and then teed up former Arsenal forward Theo Walcott to double the lead.
Gabriel Martinelli pulled a goal back, but the hosts looked down and out when substitute Duje Caleta-Car headed home in the second half.