Virgil van Dijk was left frustrated after Saints failed to convert their dominance into a victory against Internazionale.
Claude Puel’s side had a number of chances across both halves as well as enjoying more possession than their hosts.
But they fell to a sucker punch from Antonio Candreva on 66 minutes, in what was their first defeat in eight outings.
van Dijk said: “It’s very tough. I think we were the team who deserved the most obviously and to concede a goal from their only chance was frustrating.
“We should have buried the game in the first-half and there was only one team who deserved the win, but that is what happens if you don’t score your chances.
“I had a big chance with my left foot and I was unlucky but we should have already finished the game but now we need to move on and be ready for Manchester City.”
Internazionale were reduced to ten men late on when Marcelo Brozović was shown a second yellow card for a foul of Pierre-Emile Højbjerg.
And reflecting on the goal as well as Saints’ late flurry to try to force an equaliser, van Dijk added: “I think we should have stopped the cross for their goal and then me and Maya have the striker but there was a lot of movement.
“They dropped deeper and wanted to defend their 1-0 win and for us it was a case of getting the ball quick, find space and get some balls in the box.
“We looked dangerous but as I say, the game should have been won before that.”