Koren recalls World Cup bawls and bust-ups
The current side qualified via a shock play-off victory over Guus Hiddink's Russia. They also finished above the highly-regarded Czech Republic and Poland in the qualifying group, conceding just four goals in 10 games and beat group winners Slovakia home and away.
This feel-good factor is a far cry from 2002 when striker Zlatko Zahovic, the country's record goal-scorer, had a heated dressing room row with then coach Srecko Katanec that led to his early flight home.
Further, the team lost all its matches, to Spain, South Africa and Paraguay.
"It was a massive thing for our country and the national team, being in the World Cup," team captain Koren told Reuters.
"But some bad things happened.
"First of all we didn't get the right results, which was disappointing because we expected to get some points.
"The main thing was that there were some problems between the manager and the players and that is good for nobody. Now, it's completely different."
The 2010 Slovenia team is not in total harmony as there has been conflict with its football federation over reward payments but relations between players and management are apparently healthy.
England, the U.S. and Algeria await them in the group phase.
Midfield schemer Koren, 29, whose West Bromwich Albion team won promotion to the Premier League this month, was taking a detour from his usual after-training routine in which - on a sunny day - he would visit a local park with his wife and two sons to kick a football.
Back home he enjoys playing tennis with friends. Dressed in a denim jacket, T-shirt, jeans and white pumps and approaching the end of a marathon two-hour barrage of questioning from the world's media, Koren appeared relaxed with Slovenia's current position, particularly after five wins in six matches.
The Slovenia story is no longer one to be embarrassed about, but proud of, he said.
"Nobody is thinking too much about what happened in 2002. We are playing a different style. Before we only had one star in the team (Zahovic). But now we try to play more like a team and don't have one star.
"We are very good friends and have a good team spirit. You can't compare those two teams. We just want to show the people that we are good enough and get enough points to get through the group stage."
He added: "It's difficult to say what is realistic. A couple of months back when we met Russia in the play-offs, everybody was saying we are the underdogs and will lose this game and Russia is in the World Cup - this was being said all over the world.
"But we are in the World Cup and we deserve that. We are full of confidence."
Koren's popularity with the media pre-World Cup has sky rocketed. A club spokesman revealed he would normally give maybe one interview to local media every three weeks.