Following Enzo Maresca's Chelsea departure in early January, the Premier League side moved quickly to appoint Strasbourg boss Rosenior. The former Hull City coach expressed his delight at joining the Blues - who, like Strasbourg, are also owned by BlueCo - but also expressed his gratitude to the Ligue 1 outfit.
After being sworn in at Stamford Bridge, he said: "I was fully focused on Strasbourg's last match but what has happened since is I have been given permission - one of the biggest clubs in the world - who are Club World Cup champions. It is an honour to speak to a club like that and on this day it looks like I will be the manager of that football club. It's an unbelievable opportunity at an incredible club, the world champions, and one I just couldn't turn down. And I can go home, and see my kids. I have made a sacrifice being away from them."
He added, "It's been the best 18 months of my professional career here at Strasbourg. I have met some incredible people and none of that happens without the hard work of everyone connected with this football club."