The Leeds boss studied Borussia Dortmund over the summer... and Red Bull Leipzig.
One of them was Red Bull Leipzig...
Red Bull, of course, have frequently been linked with a takeover of Leeds from Massimo Cellino, being tipped for a £60 million deal earlier this year by the Daily Mirror.
It's intriguing, then, that Rosler will have been seeing how one of their club sides operated over the summer.
The German says he received plenty of job offers at the end of last season but didn't want to 'dive in too early,' eventually choosing the right place to go in Leeds.
While he was out of work, Rosler watched Borussia Dortmund train and also went to Leipzig.
The Leeds boss is quoted as saying by the Star: "I had a few offers to be honest. I had offers from two League One clubs and 1860 Munich. And there were possibilities for me at the end of last season to go in when clubs were struggling.
"But I didn’t want to dive in too early. I used the time well in my opinion. I watched a lot of players. I travelled a lot and watched a lot of football, also abroad. I went to Borussia Dortmund and watched them train at La Manga for a week.
"I went to Red Bull Leipzig. It allowed me to study the game and be refreshed with new ideas going into a new job. I got offers but it was very important for me to get the right one."
The 46-year-old will now have had several weeks' experience of how a club is run by Mr Cellino - might he have already noticed several fundamental differences between a Red Bull club and Leeds?
Either way, Rosler looks as though he's become rather well traveled ahead of taking the Whites job. Now to put what he's picked up along the way into practice...