Nkunku made a late cameo in Leipzig's 3-0 win at Wolfsburg on Saturday, setting up a goal for Konrad Laimer after a 98-day absence which saw him miss France's run to the World Cup final in Qatar.
His 21 minutes on the pitch Saturday has him in line for a return to the starting eleven, and manager Marco Rose (46) said it shows how valuable the star forward is to Leipzig's hopes.
"You could see how good it was for us that Christopher is back," Rose said after the victory.
"With him on the pitch, we are more unpredictable as a team."
Nkunku suffered a knee injury in November in France's last training session before departing for Qatar, one of a series of injury blows for the team in the tournament run-up.
Despite missing five league matches, Nkunku still sits atop Leipzig's goalscoring charts this season with 12 - just one less than Bundesliga season leader Niclas Fuellkrug.
Crucial comeback
Nkunku's return is crucial to any hope Leipzig have of springing an unlikely upset on the Champions League favourites and making it past the last 16 for only the second time in club history.
In particular, Leipzig will need Nkunku's speed and creativity to break down a City defence which has conceded just two goals this Champions League season - the equal lowest in the competition alongside Bayern Munich.
Earlier in February, Rose heaped praise on Nkunku's unique qualities as he worked towards a comeback, calling the Paris Saint-Germain junior "a difference maker."
"He simply has qualities that are not so common in the Bundesliga, in Europe and in the world," Rose said at the time.
Courage against Haaland
On the opposite side of the pitch to Nkunku on Wednesday will be star City forward Erling Haaland (22), who has 32 goals in 31 games since moving to the Etihad Stadium from Bundesliga rivals Borussia Dortmund in the summer.
Haaland scored more goals against Leipzig during his time in Germany than any other opponent, with six goals in four games, including two in Dortmund's 4-1 German Cup final win over the Red Bulls in the 2020/21 season.
Rose will know Haaland's threat better than most, having coached the then-18-year-old at Red Bull Salzburg and later at Dortmund.
The man tasked with keeping Haaland in check on Wednesday, Leipzig captain and centre-back Willi Orban (30), was confident the home side could keep the Manchester City striker at bay.
"Of course, it will be a big challenge for us. But we can do it - we showed that against Real Madrid," he said.
"He (Haaland) is difficult to defend of course, but with courage, you can do it," Orban added.
Leipzig beat the reigning European champions 3-2 at home in October to seal their qualification for the group stage.
Leipzig forward Emil Forsberg (31) - who scored the opener against Wolfsburg on Saturday - mirrored Orban's optimism.
Speaking after the match, Forsberg said the "beautiful and important win" would give his side "self-confidence" for the City clash.
"We're looking forward to an awesome game. We want to go out and win."
