Merciless Bayern hit 10 against amateurs Auckland City at Club World Cup
Kingsley Coman, Michael Olise and Thomas Mueller all netted twice, while Sacha Boey was on target too for the German champions in the game in Group C, which also features Boca Juniors and Benfica.
Harry Kane started but didn't get on the scoresheet before being replaced just after the hour mark by Musiala, who netted his three goals in the space of 18 minutes towards the end.
"We have to remain modest but it was important to be able to say that we took the game seriously," said Bayern coach Vincent Kompany.
"It was a good first match at the tournament, but of course challenges are going to grow and it's going to become more difficult."
It was a stroll in the park in the midday sun in Cincinnati for Kompany's side, with France winger Coman scoring twice in the opening 21 minutes either side of goals by compatriots Boey and Olise.
Coman's sixth-minute breakthrough goal was the first of the tournament following the 0-0 draw between Inter Miami and Al Ahly in Saturday's opening game.
Mueller got the fifth and Olise's second of the afternoon made it 6-0 in first-half stoppage time for the Bundesliga heavyweights.
Olise's strike for the sixth was the pick of the day's goals, as he came in from the right before curling a shot on his left foot into the far corner.
Super-sub Musiala
Auckland City managed to stem the tide for much of the second half before Musiala came on and took centre stage, his three goals including one from the penalty spot after he had been fouled.
Mueller, who will leave Bayern after the tournament, made it 10-0 in the 89th minute with his 250th goal for the club.
The result confirmed the enormous gulf between one of Europe's giants and an Auckland side who have won the Oceania Champions League 13 times but whose amateur players had to take unpaid leave to travel to the United States for the tournament.
"This is the reality of football against one of the world's top teams," admitted City's interim coach, Ivan Vicelich.
"It is a dream for players coming from an amateur level to play in this environment.
"We knew it was going to be a very difficult game, playing against one of the top teams in the world, potentially one of the favourites for the Club World Cup, so we are just really proud of the players' efforts."
However the result made it an ideal start for Bayern, who won the Club World Cup twice in its former seven-team guise, in 2013 and 2020.
They have recorded bigger victories in the past in the German Cup, but the 10-goal winning margin equals their best ever in the Bundesliga, when they beat Borussia Dortmund 11-1 in 1971.
Bayern, who gave new signing Jonathan Tah a debut in central defence following his recent arrival from Bayer Leverkusen, play Boca in their next match in Miami on Friday.
Auckland City take on Benfica earlier the same day in Orlando.