Bayern started the day in mid-table following defeat to Hoffenheim last month, but victory in Bielefeld propelled them to second
Robert Lewandowski and Thomas Mueller both scored twice as Bayern Munich banished their early-season blues with a thumping 4-1 win over Bundesliga minnow Arminia Bielefeld Saturday after a "crazy" first half.
Treble winner Bayern started the day in mid-table following a shock defeat to Hoffenheim last month, but victory in Bielefeld was enough to propel them back up to second place.
The champion burst out of the blocks and had an early penalty appeal turned down before Mueller bundled in the opener on eight minutes.
Lewandowski doubled the lead shortly afterwards, smashing the ball in from the edge of the area after a sharp cross from Leon Goretzka.
The Poland striker linked up with Mueller to make it 3-0 just before half-time, and returned the favor after the break with a pinpoint cross to set up Mueller's second.
Japan winger Ritsu Doan then pulled one back for Bielefeld on the break, the PSV Eindhoven loanee netting his first Bundesliga goal since moving to Germany in the summer.
Yet despite a late red card for Corentin Tolisso, Bayern were untroubled in the final stages and can now turn their attention to Wednesday's Champions League opener against Atletico Madrid.
Hansi Flick's side now sit level on points with third-placed Borussia Dortmund.
Elsewhere, Lucas Alario's first half header sealed a 1-0 win for Bayer Leverkusen and extended second-from-bottom Mainz's miserable run to four defeats in four games.
Promoted side Stuttgart continued their good start to the season, as Marc-Oliver Kempf and Gonzalo Castro fired them to a 2-0 win away to Hertha Berlin, while Werder Bremen held Freiburg to a 1-1 draw in the south west.
Freiburg took the lead early on through Philipp Lienhart and had a second goal ruled out for offside before Bremen's Niclas Fuellkrug levelled the scores from the penalty spot.
In Saturday’s late game, Wolfsburg chalked up a fourth successive draw away to Borussia Moenchengladbach, as Wout Weghorst struck late to cancel out Jonas Hofmann’s second-half penalty.