Vidal has scored in four successive Bundesliga games since Heynckes criticised his fitness levels last month.

The Chile international headed in the only goal of the game on Saturday after 20 minutes -- nodding home an exquisite Joshua Kimmich cross at the far post.

"It's to Arturo's credit," Heynckes said at a postmatch news conference. "He has played many outstanding games for Bayern in the last few years, but has been a little out of sorts recently. The player has to make the change himself -- naturally with my help."

The win in Frankfurt ensures Bayern will head into the winter break leading the Bundesliga for a seventh consecutive season, stretching their advantage to eight points over nearest challengers RB Leipzig, who could only draw 2-2 at home to struggling Mainz.

"The autumn championship is not important, what is important is the team are back playing good, attractive football again and we are able to win games like today," Heynckes said. "I won't deny the table is very pleasant to look at with our lead, but we won't get carried away celebrating."

However, the 72-year-old felt there were mitigating circumstances behind Bayern's patchy display.

"Of course, we have different ambitions on how we want to play, but Thomas Muller is only just back after a six-week injury break," he said. "Franck Ribery was out for nine weeks -- only playing his second game and has not played a full 90 minutes.

"I had to take off Kingsley Coman as well because he was still carrying an injury from Tuesday [against Paris Saint-Germain]. I also did not allow Robert Lewandowski to start because he is still battling a problem with his patella. David Alaba was also injured for a long time and recently had another two-week break."

Heynckes added: "I know what is and what isn't possible, but it's vital to win these type of games. We made five changes plus we had Tom Starke in goal today. Of course, we have a very good squad but with these type of problems, you cannot expect to perform like we did on Tuesday against PSG."

Heynckes confirmed that goalkeeper Sven Ulreich had injured his adductor in the warm-up, meaning a surprise 100th Bundesliga appearance for veteran Starke -- who had retired and become a coach at the club's academy in the summer. The 36-year-old was asked to come out of retirement following the injury to first-choice keeper Manuel Neuer.

Heynckes said: "I have to say Tom performed brilliantly considering the circumstances."

Bayern's Javi Martinez joked after the game that "Starke looks like he is 50 but trains like a 28-year-old."