Ronald Koeman was less than pleased with the performance of Southampton as they suffered a 3-0 loss at home to Everton.
A brace from Romelu Lukaku and a late strike from Ross Barkley clinched all three points for the visitors on Saturday.
Koeman was far from impressed with his side's defending, especially for Everton's crucial second goal.
The Dutchman said: "The first half was not good, maybe we had one or two good chances but the performance of the team was not what we expect. Not defensively. We weren't aggressive enough in our defending and gave Everton too much space to play football.
"The best example was the goal which came from our corner kick. You need better organisation, or at least you need better reaction from the players.
"We need to learn from that because at this level they will punish you for these kind of mistakes."