The Saints have been on a poor run of form over the best six weeks having not won since their away victory on November 7th against Sunderland. Since then, Koeman's side have lost five games and drawn one in all competitions.
However, speaking to the press ahead of the Saints' Boxing Day clash against Arsenal, Koeman has called for his side to be more ruthless and stronger.
Koeman said: "We know we are in a difficult situation. We had a bad run last year but not like this one. It’s always difficult because we lack in confidence and belief.
"Sometimes, if we get a negative moment in the game then the team is doubting about the qualities and the team [are] not playing what they can. They have to realise that we can play good football. In the part of the game [against Tottenham] when we’re really good, creating chances, then we have to score. Defensively we need to be stronger, we need to be more ruthless than we were against Tottenham"
Despite admitting last week that he was worried about Southampton being sucked into a relegation battle, Koeman said that because of a tight Premier League table, a win could send his side back into the top half.
"If you have two wins, you fight for European football. If you lose twice from now, you will fight against relegation. That’s the Premier League at the moment. You have to be realistic. You have to see both ways.
"We know the Premier league is a tough competition. You can win against everybody, you can lose against everybody."
Saints come up against an Arsenal side on Boxing Day that many are touting as potential champions. Saints were victorious on New Years Day in the this fixture last campaign but Koeman believes this Arsenal side is different to last season.
"Now if you watch Arsenal, maybe it’s more difficult to win against Arsenal than it was last year. But, Arsenal is a little bit different now than it was.
"In my opinion, it’s more a counter attacking team than it was before. One of the big strengths in the team is transition to attack. It’s so fast with good movement, with very good players. That’s one of the reasons that they are more regular in results in the last few weeks. They are looking stronger than they were last year."
Despite a tough game against Arsenal, Koeman is confident that his side can return to winning ways and put an end to their poor form.
"We need a win. The best medicine to get confidence back is winning. The final whistle makes a different world if you win or lose. Still I think and I believe we can turn it around."
Yet again, Koeman was asked about reported interest in Victor Wanyama but the Dutchman labelled a possible January transfer to Arsenal as "impossible".
"They can prepare what they like to prepare. Don’t spend time preparing to buy a player of Southampton because it’s impossible"
Koeman also confirmed that Maarten Stekelenburg should be available for selection after missing out on the last two matches with a toe injury.