And goalkeeper Danny Vukovic made it a red letter day for Australian football after making his long-awaited comeback from injury by helping his club Genk to victory.
It was a baptism of fire for Muscat, who is the only Australian head coach of a men's team in Europe after playing a major part as a player, captain and coach in making Melbourne Victory an A-League powerhouse.
Muscat had issues to resolve before obtaining permission from the Belgian authorities to take charge of a professional club.
While his application for his coaching licence to be recognised was being processed, he was given the role of technical director of the club they call the 'Canaries' but that did not hinder his preparations for the season.
Muscat's pre-season work with the help of Australian assistant Luciano Trani has paid dividends with a vital first-up 2-1 win over fancied Gent that gives him and his players plenty of confidence.
Sint-Truiden face a stiffer challenge in their next match away to Anderlecht next Monday (AEST).
It also was a day of huge relief for Vukovic who will now forget all the long hours of lonely rehabilitation after a freak training injury that kept him out of the game for a whole season and robbed him of the chance to play in this season's truncated UEFA Champions League.
Vukovic completed his recovery when he started and starred for Genk in a come-from-behind 2-1 win at Zulte Waregem.
"I feel the injury is definitely all behind me now and it was just great to be back," Vukovic said after being named man of the match by a supporters' group.
"It was hot out there yet I felt good and sharp despite the tough conditions. It was 36 degrees.
"I was confident and focused, and the fact we were playing without supporters helped me communicate beautifully with my defenders."
Genk's next game is at home to promoted Oud-Heverlee - formerly Leuven - on Sunday (AEST).