With a third of the German league season still to play, Bayern hold a commanding seven-point lead as all their main rivals lost at the weekend.
Their nearest challenger, RB Leipzig, kept Bayern off top spot for three weeks late last year after a flying start to their first Bundesliga season.
But when the sides met in Munich last December, Bayern floored Red Bull-backed Leipzig with all goals coming in a commanding first-half display in a 3-0 win.
On Saturday, their rivals' defeats played into Bayern's hands.
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"Curtains closed in the Bundesliga," commented Munich-based newspaper Sueddeutsche Zeitung.
"We are delighted, it was a great day in the league for us," beamed Bayern's chairman Karl-Heinz Rummenigge.
But their seemingly unstoppable path to a fifth title in a row has turned the Bundesliga into a one-horse race.
"If Bayern Munich wins 10 or 15 consecutive titles then it will become a problem, but we are not there yet," Christian Seifert, director of the German Football League (DFL), recently told reporters.
Borussia Dortmund hammered them 5-2 in the German Cup final on May 12, 2012 -- a week after Borussia were confirmed league champions with Bayern eight points behind.
- Mourinho's swipe -
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Since then, no German rival has got close to the Bavarians.
In the 2012/13 season, with Jupp Heynckes as coach, they became the first German club to win the treble of European, league and cup titles.
Bayern won the Bundesliga with a 25-point gap over nearest rival Dortmund.
The domination continued in each of Pep Guardiola's three years in charge, securing the 2013/14 title that March with a record seven games left to eventually finish with a 19-point gap.
thinly-veiled swip at Guardiola, now at Manchester City, by saying Bayern 'bought' titles in Germany before the seasons even kicked off.
"In Germany, Bayern Munich start winning the league in the summer. Every year they buy their rivals' best player. One year it's (Robert) Lewandowski, the next year it is (Mario) Goetze. The next year it is (Mats) Hummels," said Mourinho. Next season, Germany internationals Niklas Suele and Sebastian Rudy will be joining Bayern from Hoffenheim.
But despite their lead, Bayern have looked less than impressive under Guardiola's successor Carlo Ancelotti this season.
- 'Bayern's luck' -
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Guardiola was often a frantic figure on the sidelines, cajoling, urging, encouraging and demanding effort from his Bayern players.
Ancelotti is a more relaxed figure, trusting his star-studded line-up to sort out their own problems on the pitch.
Bayern lacked urgency and creativity in Saturday's 2-0 win at strugglers Ingolstadt as Arturo Vidal netted in the 90th minute before Arjen Robben added a second 60 seconds later.
"It's Bayern's luck. Or the conviction that we'll end up with goals at the end," said captain Philipp Lahm.
"From what I saw of the (Ingolstadt) game, nothing," he said.
"We did well. It will give us lots of courage and self-confidence for Wednesday."
Bayern are on a record 15-match winning streak at home in the Champions League and have won five of their last 10 games against the Gunners.
After three straight semi-final exits, the Bavarian giants are desperate to win the Champions League, but defeat to Arsenal -- meaning their first last 16 exit since 2011 -- would be a black mark against Ancelotti.