Struggling in Europe after back-to-back losses left them outside the knockout places, Musiala broke through the stubborn Benfica defence, heading in a Harry Kane assist.

Bayern were dominant in possession but carved out few clear-cut chances, lacking fluency in front of a silent home crowd who refused to sing out of respect for a hospitalised fan.

Despite the win, Bayern still have work to do in Europe, with this season's Champions League final on home soil.

The German giants sit 17th, one behind Dinamo Zagreb who they beat 9-2 in their opener. Bayern face French champions Paris Saint-Germain next in the competition.

"We had good moments. The opponent defended well. It was very important to get three points today," Musiala said after the match.

"We don't have to win every game by four or five goals. Sometimes 1-0 is enough. We had to be patient. Now we carry on and look to the next game."

Unbeaten at the top of Bundesliga table under new manager Vincent Kompany, Bayern have struggled in the Champions League this season despite the barnstorming opener against Zagreb.

A 1-0 loss at Aston Villa and a 4-1 thrashing by a supercharged Barcelona under former Bayern manager Hansi Flick had the six-time European champions outside the knockout places before kick-off.

With the match delayed by 15 minutes due to public transport issues and with their home fans silent due to a medical emergency in the stands, Bayern struggled.

Musiala and Michael Olise dribbled in from either flank but were unable to break through a Benfica side looking to sit deep and take advantage of Bayern's risky high line on the counter.

The best chance of the opening half fell to Serge Gnabry, who forced a strong save out of Anatoliy Trubin on the half-volley after 38 minutes.

As the game wore on -- and with the home fans still silent -- Bayern grew nervous, even if Benfica had few genuine chances as they looked for a first win in their 11th match against the hosts.

Leroy Sane added speed after his substitution and the former Manchester City winger would prove crucial, finding Kane who in turn found Musiala for Bayern's goal on 67 minutes, the only strike of the match.

Bayern's final match before the international break comes on Saturday in Hamburg against St Pauli.