"We weren't courageous enough in the first half".
Bayer Leverkusen star winger Leon Bailey could move on soon as the club's sporting director Rudi Voller has acknowledged there may come a time to sell the young Jamaican star.
Ribery's second-half strike was his first of the campaign, and the Frenchman was delighted to have had an impact for the leaders on a tough away trip. Arturo Vidal worked out two opportunities in the opening period but Leverkusen goalkeeper Bernd Leno was on guard twice to maintain parity.
The Bavarians kicked off 2018 with a potential banana skin but demonstrated their class as goals from Javi Martinez, Franck Ribery and James Rodriguez saw them overcome a side who had not lost in their previous 12 Bundesliga games.
Bayern took a deserved lead on 32 minutes when Martinez slammed home from close range.
Leverkusen did not appear any more of a threat initially after the break, but a moment of individual brilliance from Bailey almost restored parity in the 55th minute.
Just four minutes later, however, Franck Ribery doubled Bayern's lead, as he received the ball in acres of space on the left-wing, before cutting inside and finishing into the bottom-left corner.
Bayern seemed to be in control but Kevin Volland pulled one back for Leverkusen with a deflected shot and suddenly the home side was pressing for more with just under 20 minutes remaining.
Germany striker Volland, who is on the fringes of the national team, tested Ulreich and then took his chance. We are relaxed. The only club that can say no - and would do so - if a player attracted interest is Bayern Munich. - Bayer Leverkusen scored in its 23rd consecutive Bundesliga match - by far the best streak of any team in the division.
With Lewandowski out, burly Germany striker Sandro Wagner is set to make his first Bundesliga appearance since joining from Hoffenheim last month, reportedly for 12 million euros ($14.3m).
The defeat broke Leverkusen's 14-match unbeaten run in all competitions, dating back to the end of September, but the hosts stay fourth in the table. - Jupp Heynckes has won 10 of his 11 Bundesliga matches since coming back as Bayern coach, losing only to Borussia Monchengladbach.