Bayern and Liverpool played out a 0-0 draw in the opening leg, which took place at Anfield on February 20.
Since then, 22-year-old Coman has missed each of Bayern's last two matches as he's battled a hamstring issue.
Coman has dealt with a number of knee issues throughout his Bayern
However, the recent hamstring issue proved to not be serious and he will be ready for Tuesday's match.
"[He] handled the maximum load in training on Monday, so he is fit," Kovac said of the French winger.
"I'm very happy. That gives us an alternative, one more dimension."
Kovac added that "we have to look" at whether Coman was fit to start or would be more capable with coming off the bench in a more limited role.
Alaba, meanwhile, is set to return after irritating a tendon issue and has also missed two matches.
"So far, I assume he's ready to go," the Bayern Munich boss said.
Kovac went on to say that he sees Wednesday's clash as a "highlight game" against the "cream of world football", as Bayern look to seal a spot in the Champions League's quarter-final round.
In Bundesliga play, the club currently sits first in the league as they battle Borussia Dortmund for the top spot.