The Guinea international has hailed the former Cagliari coach's influence in Milan's return to form and has stressed the match against Juventus is a must-win game
The Rossoneri made a disappointing start to the season and even found themselves back in the lower half of the table in late November.
Nevertheless, they have climbed to third spot following a string of good results and still have every chance of securing automatic qualification for next year’s Champions League.
"We started the season badly but we have improved. This is down to the coach who has got his message across to all the players," Constant was quoted as saying on the official Milan website.
The 25-year-old then went on to discuss this weekend's Serie A game against Juventus and stressed that Milan need the full three points.
He added: "It's an important match psychologically for us. We are four points behind Napoli and now we have to do everything to win."
Milan beat Juventus 1-0 at San Siro earlier this Serie A season.