Rose, who has been in charge of the league's third-placed side since September, has been the driving force in their rise up the standings, and going into Friday night's game, they sit just six points behind league leaders Bayern.
The former Borussia Monchengladbach manager had Sommer in his side during his tenure in Gladbach and was happy for his former charge to complete his move to Bayern this week, even joking: "He called me and said if you don't take me, I'll go to Bayern."
Sommer, who was brought in to replace the injured Manuel Neuer (36), is now in contention to start the clash and make his debut against Leipzig with Sven Ulreich (34) another contender.
Speaking about Sommer, Rose said: "He is a good signing for Bayern Munich because he is a great goalkeeper, a really good guy. He is a goalkeeper with a strong game, so he fits Bayern's game. He also catches balls quite decently.
"At the end of the day, there will be someone in goal. Who, I don't care. We try to shoot past left and right."
It is a big game in the German title race, with Leipzig able to close the gap on their rivals with a win, but Rose does not want to pile more pressure on the fixture ahead of kick-off.
The coach explained: "I don't have to start ranting here before the game against Bayern and talk about the championship and 'fire away' and 'full throttle' - we want to win the game tomorrow.
"We have to be very resilient and passionate in defence. I think we also need to make sure it doesn't become an old-school end-to-end game. That would play into Bayern's counter-attacking strengths."
"You can see relatively clearly from the table what's at stake."
