Koeman watched on as his side hit eight past Sunderland to show the perfect response to defeat against Tottenham Hotspur before 16 players departed for the international break.
Saints’ boss was delighted with what he had watched, praising the performance of his players in the second half against Gus Poyet’s side.
Speaking to youtube.com/southamptonfc
, Koeman said: “I am a little bit in shock because 8-0 is not a normal Premier League result.
“It was different in the beginning of the game because I was not happy with how we started. Sunderland were the dominant team and had some good possibilities but sometimes you need luck in life.
“The first own goal changed a lot in the game and in the second half we were amazing. We played great football and scored great goals, fantastic goals.
“The most important thing in my opinion is that we had the spirit until the last second of the game and that shows a lot to me from the players.
“You always try that from the bench, to give them the spirit to go on. I put two new players into the game and they were motivated to bring a new spirit to the team.”
Koeman has overseen some impressive performances already since arriving at St Mary’s but there was little doubt in his mind that this was his best day in charge so far.
With 16 points on the board from the opening eight games, Koeman says the team can go far this season, and was pleased to see his players turn their attentions immediately to the next game.
“Of course, it’s the best by far,” he added. “The happiness of the crowd, that’s football and that’s the reason I am the manager of Southampton and why the players are still players of Southampton.
“If we keep our feet on the ground and do the same what we have done until now, it can be a great season. We have to fight and work every day to have a good team and to keep the organisation.
“It was very easy to say ‘have tomorrow off’, but we will do a training session. We can be proud of the ambition of the players, they are already talking about next Saturday and that means a lot.”