Chelsea are two points off the automatic last-16 places with two games to go after three wins, one draw and two defeats from their opening games under former manager Enzo Maresca.
Chelsea's illness continues to spread
Now, Rosenior takes the reins as he tries to push the Conference League and Club World Cup champions into the next round.
The Englishman first spoke on team news and revealed that Enzo Fernandez will miss the clash as a bug continues to spread around the camp.
"Enzo Fernandez was ill yesterday and missed training. Estevao has been back in. Jamie Gittens is back in. Malo Gusto is back involved - another outstanding player."
Continuing on the theme of Fernandez, Rosenior responded to rumours linking him with a move away from the club this January which he rubished without hesitation.
"It means nothing to me. When you are a world-class player there will always be speculation you cannot control. Enzo has been outstanding and he has surprised me in a good way - in terms of what he did on Saturday, covering the ground he did when he was ill.
"He is a Chelsea player, he is very important to me and hopefully we will have a winning relationship in the short-term and long-term."
Rosenior backs Delap to succeed
Former Hull City boss Rosenior worked with now Chelsea striker Liam Delap whilst with The Tigers back in the Championship. The England striker has just 1 goal in 13 Premier League appearances this season and has struggled to adapt with the West London side. Despite this, Rosenior has backed the striker, who he knows how to get the best out of.
"I have been delighted, not just with Liam but with lots of players I've worked with throughout my career. I like to keep a track of players I have worked with and it was so good to see him perform at a level I believed he was capable of in the Premier League. so it was not a surprise to see him make another move up to Chelsea.
"I am not surprised, but he also knows I will keep pushing him to keep improving and if he can do that, I am confident that he will have an outstanding career."
Finally, Rosenior commented on what it feels like to manage in the Champions League: "Your dream, as a player or manager, is to be at the top of the game - the Champions League is a signal of that. It's not about me; my focus is on winning the game and being successful here."