Saints boss Mauricio Pochettino said his team were taught a “great lesson” after nearly throwing away a three-goal lead against Norwich.
Saints led 3-0 with five minutes left at St Mary’s, but then gifted the Canaries two goals in a matter of seconds to set up a nervous finale.
Sam Gallagher’s strike deep into injury time ensured a 4-2 win, but Pochettino said they must learn from their late lapse in concentration.
“It’s a great lesson that we have to learn from today’s game,” he said. “We’re a young side that’s still growing, and the main lesson today is that, obviously, the game is not finished until the final whistle has blown.
“We’re well satisfied with the game at 3-0, but it goes to show that when you lose a little bit of focus, you lay your guard down, we basically made two quick mistakes.
“We conceded two soft goals and, again, it is a lesson we have to learn.”