The two sides are set to meet in the Premier League in the coming days, with the Blues flying high in the table and Ipswich in a relegation battle.
However, Maresca knows the two men could have been in different positions, as McKenna was also a Chelsea target in the summer before they signed Maresca from Leicester City.
He stated: "He is doing fantastic since he joined Ipswich. They are doing top. Even this year, they are doing well so congratulations to him for the way he is doing everything since he joined the club."
On the game itself, he added: "I think all the Premier League games are complicated; no matter the other team. You see every game we play, it is always complicated. You see the other team, you struggle to beat teams and I think the Ipswich game will be exactly the same."
On the importance of getting a win, he finished: "Very important. We are going to try to prepare the game in the way we try always - to win the game. We have a bad feeling about the game we just lost against Fulham and hopefully we can come back with three points after this game."