The midfielder lauded the Belgian star's past contribution to the club's cause, citing how difficult it will be for anyone to come close to repeating such heights
"Nobody can replace Hazard," claimed Mavuba to Footlille.com. "We have lost a big player."
The 21-year-old Belgium attacker departed Rudi Garcia's outfit earlier this summer in a massive 40.5 million euros move to the Champions League winners, and the former Villarreal man was quick to pay tribute to his old team-mate.
"The force at Lille has always been a collective one, and since the transfer made both the club and Hazard a little more money, there was no choice," Mavuba explained.
"Salomon Kalou is a different type of player, but he will be an asset in helping us meet our objectives."
Hazard scored 20 goals in 38 Ligue 1 appearances last season, firing the Metropole side to third and subsequent Champions League play-off qualification.