Chelsea cruised to a 4-0 victory at Stamford Bridge, climbing back into the top four while deepening Saints’ relegation woes.
Goals from Christopher Nkunku, Pedro Neto, Levi Colwill, and Marc Cucurella sealed Southampton’s 22nd loss of the season.
Post-game, he said: "I think we did really good the first 25 or 30 minutes. We had two big chances with Paul and we were very competitive with them.
"Then we conceded a set-pieces goal and the first one and third one in one transition and it became really difficult after the first half.
"It was almost finished because 3-0 against Chelsea is a lot, but I think the guys gave everything they have in this moment and that's it.
"It is a really tough moment for everybody, for the players, for the club but it has to be energy for the future," continued the boss.
"All these negative moments to accumulate energy and try to do better in the future."