England must beat Slovenia to assure themselves of a place in the last 16 of the FIFA World Cup™, while Koren's men need only a point to confirm their progress from Group C.
Their only previous meeting came at Wembley last September, a game England won 2-1 but only after Swedish referee Jonas Eriksson had awarded a dubious penalty as Wayne Rooney and Bostjan Cesar jostled in the box.
England's second goal also owed much to good fortune as it took a heavy deflection off Slovenia midfielder Aleksandar Radosavljevic before finding the net. Zlatan Ljubijankic, the scorer of Slovenia's second goal in a 2-2 draw against USA yesterday, later pulled one back.
Koren insisted the sole purpose of the fixture was for Slovenia to find their form before a FIFA World Cup qualifier against Poland four days later and said: "We didn't really prepare for that game and we still gave them a really good game. They were lucky to get a result, the referee was up and down when we played them at Wembley.
"It will not be about revenge for us on Wednesday, it was a while ago since we played them. It was completely different, because we were just preparing for a game in the qualification group, we didn't think too much about the England game.
"But we're not thinking about that game, it is already behind us. This is a new opportunity for us and we will be up for it."
Koren and co were certainly up for it in the first 45 minutes of their match against the United States, racing into a 2-0 interval lead with playmaker Valter Birsa particularly outstanding.
They were eight minutes away from securing a last 16 place when Michael Bradley made it 2-2, and survived a late scare when a Maurice Edu goal for the Americans was disallowed.
"In the first half we played really well, we got two goals and the game looked easy for us," Koren added. "Still in the second half we were in control and I think we were disappointed in USA. They didn't show too much good football - it was lucky for them to score two goals.
"The England game is a different story, but we will go through the (USA) game and see where we were not good enough and try to do better against England."
Slovenia have every right to be confident for the Group C decider - within the space of eight months they have eliminated a Russia side, semi-finalists at EURO 2008, in a South Africa 2010 qualification play-off and come close to beating the US.
"Of course, you expect every game to be hard," Koren said. "There is nobody in particular we will have to watch out for when we play England; we will play team against team, 11 against 11, the game starts at zero. We are full of confidence because we have four points so far, we are not worried."