An early Aymane Barkok shot that whistled wide was as close as Mainz came to laying a glove on Bayern in a one-sided first half. Finn Dahmen had already been called on to deny Leroy Sane, when Cancelo took centre stage with an inch-perfect cross for Eric Maxim Choupo-Moting to volley home at the back post. Jamal Musiala curled in a sublime second, before Joshua Kimmich sent a free-kick against the woodwork. Sane added a close-range third on the stroke of half time, after smart play from Choupo-Moting.
Bayern went close to extending their lead as the contest ticked towards the hour mark, with Alexander Hack thwarting Thomas Müller twice in quick succession. Anthony Caci fizzed an effort narrowly past the upright in response, but that was pretty much all the partisan home crowd had to get excited about. After Ryan Gravenberch warmed the palms of Dahmen, fellow substitute Alphonso Davies rubbed salt into the wound with a late header. Alexander Hack collected a second bookable offence as Bayern cruised through and to their first win of 2023.
Bayern are through to the quarter-finals for the first time since winning their record-extending 20th DFB Cup in 2019/20.
The win ends a run of three straight 1-1 draws, and marks Yann Sommer’s first clean sheet for the club.
Davies has more goals against Mainz (three) than any team he's faced.
Musiala scored his first goal of 2023, and 13th in all competitions this season.
Choupo-Moting has 13 goals for Bayern in 2022/23: seven in the Bundesliga, three in the Champions League and three in the DFB Cup.
Müller made his 63rd DFB Cup appearance, equalling Sepp Maier’s club record in the competition. His 53 wins is an outright DFB Cup record.
After three consecutive 1-1 draws to start 2023, Bayern have finally rediscovered that winning feeling. The laid the foundations with a strong first-half display, and although Mainz were much improved after the break, Davies' late header capped an all-round impressive display from Julian Nagelsmann's side, who take their place in the DFB Cup quarter-finals.
Down to 10
Mainz must play out the remainder of the match with 10 men after Hack is sent off for a second bookable offence.
Kimmich curls in a cross from a central position and Davies leaps to meet it on the penalty spot, expertly guiding a header in for his second goal of the season, having also found the target against Mainz in the second round.
Musiala sprints forward into space over almost half the length of the pitch. He plays it to his left to Davies, who in turn finds Gravenberch on the edge of the box. He shoots quickly but it lacks the power to beat Dahmen.
Gravenberch is back on the pitch now and is looking to run off the knock he took to his ankle.
The Dutch midfielder receives treatment after a hefty challenge with Hack. He limps off to the side of the pitch but appears to be ok to continue.
The hosts are not aiming for damage limitation here: they've played very well in this second half and are getting forward boldly. The introductions of Onisiwo, who hit a hat-trick in the Bundesliga at the weekend, and Ingvartsen, are signs that they're going for a goal.
Mainz's best chance of the game as Caci curls a shot from the left towards the far corner. Sommer is worried enough that he hurls himself at it full stretch but he can't reach it. The ball fizzes narrowly wide of the post.
Another nice run by the veteran attacker, who is again found by a clever pass from Musiala. This time Hack intervenes before he can get a shot away though.
Müller goes close
A lovely, swift attack by Bayern almost ends in a fourth goal. Musiala slots the ball into the path of Müller on the left and his shot is cleared by a combination of Dahmen and Hack.
The home side already look very different. In the first half they were too passive and timid, but now they're not backing off the Bayern players at all; quite the opposite, they're getting properly stuck in as they seek a foothold in the game.
Here we go again
No changes from Bayern during the interval but Mainz have brought on two fresh faces in Hack and Lee.
Kimmich delivers a corner from the right and finds Pavard on the edge of the six-yard box, but the Frenchman can't steer his header on goal.
The Mainz defender limps off with what looks like a groin injury. He's struggled against Coman and Müller tonight so may be secretly breathing a sigh of relief that his torment is over. Danny da Costa comes on in his stead.
Cancelo once again causes havoc in the Mainz box with a whipped cross from the right. It's just too strong for Choupo-Moting, while Müller is outmuscled at the back post before he can prod it in from close range.
Müller flicks on a long ball forward and finds Musiala, on the left-hand side of the box. The teenager shimmies past Hanche-Olsen and drills a low, left-footed shot into the far corner for his first goal of 2023.
Mainz can't be faulted for their effort but they just can't keep hold of the ball at present. Aside from Barkok's curler a little while ago, they haven't posed much of a threat.
The Mainz defender is cautioned for holding Coman with both arms wrapped around the French winger.
Choupo-Moting now has 13 goals for Bayern this season: seven in the Bundesliga, three in the Champions League and now three in the DFB Cup. He hit a double in the last round as Bayern overcame Augsburg 5-2.
Choupo-Moting might have been the scorer but this goal is all about Cancelo. Kimmich spreads the ball to the deadline-day arrival wide on the right. He jinks past his marker and curls a teasing, deep ball over Dahmen to the back post, where Choupo-Moting hits it in on the volley from close range. Superb stuff!
Müller's cross from the right is touched on by Sane to Coman at the back post. He skips past his marker and gets a shot away but Dahmen spreads himself big and makes a fine save.
Over from Barkok
A nice break from Mainz as they get at Bayern at pace. The ball falls kindly for Barkok, on the left-hand corner of the penalty area. He tries to curl his shot towards the far post but gets too much on it and the ball sails harmlessly over.
Mainz are packing five men into the defence whenever Bayern get into their half, with four midfielders coming together in the centre to block the passing channels.
Cancelo - who seems to be playing more as a right winger at the moment than as a full-back, flicks the ball forward into Sane's path. He gets to the byline but can't quite dig out a cross.
Here we go!
Bayern, playing in their dark away strip, get the ball rolling in Mainz!
Head to head
These teams have met 37 times previously, with Bayern winning 27 of those to Mainz's six. Bayern recorded 6-2 victory when the teams faced off in the Bundesliga in October last year, but Mainz have won their last two home games against the Reds (3-1 and 2-1). The two previous cup encounters both went Bayern's way, however, most recently in 2006.
More on those teams
Cancelo goes straight into the Bayern side, but not at right-back. Instead, he's deployed on the left, with Alphonso Davies making way. Benjamin Pavard replaces Josip Stanisic in the only other change to the side held to a 1-1 draw by Frankfurt at the weekend. Mainz show three changes, with Aaron Martin, Anton Stach and Aymane Barkok preferred to Stefan Bell, Jae-Sung Lee and Karim Onisiwo.
"It's a knockout game - the winner goes through," Bayern's head coach observed at his pre-match press conference. "Of course we want to win the cup. We have to take the step tomorrow in Mainz, which won't be easy. Mainz will always put pressure on at home, because of our results and because it's a knockout game. The crowd will spur them on. It's the Mainz way, they won't just park the bus. But they will have periods of sitting deep and playing on the counter. We're prepared and we hope we have the right solutions for the game."
Watch: Cancelo set for debut
Joao Cancelo is in line to make his Bayern debut after securing a loan move to the record champions from Man City yesterday.
How they got here
Erzgebirge Aue and Lübeck suffered 3-0 defeats at the hands of Mainz across the opening two rounds of this season's DFB Cup. Bayern have scored five in each of their ties, beating Viktoria Cologne 5-0 and Bundesliga rivals Augsburg 5-2.
Watch: Mainz 5-2 Bochum
A Karim Onisiwo hat-trick helped Mainz snap a six-match winless run at the weekend. The 05ers are up to 11th in the Bundesliga, 14 points worse off than leaders Bayern.
Watch: Bayern 1-1 Frankfurt
Bayern are still the hunted, but they have five teams hot on their heels after dropping points against one of them, Frankfurt, at the Allianz Arena on Saturday.
Mainz could be playing Bayern Munich at an ideal time. The record champions have started 2023 with three successive Bundesliga draws - will their lean patch continue in the DFB Cup last 16? Stay tuned to find out.