The hosts find themselves in a Champions League position under their new manager, with the visitors sitting just one place behind them as they unexpectedly continue their strong form from last campaign.
Match preview
After a disappointing campaign in 2020-21, Leverkusen have started the new one brightly under manager Gerardo Seoane, who arrived in the summer from Swiss champions Young Boys.
Three wins in the opening five matches see this weekend's hosts sitting in fourth place - a position they will be hoping to hold onto for the remainder of the campaign.
Although only early in the campaign, the signs are positive for the new man, and with 15 goals scored in the opening games as well, he has got his side playing some entertaining football to go with the results as well.
The first setback was a 4-3 defeat at home to fellow European hopefuls Borussia Dortmund two weeks ago, but following that up with a 3-1 victory away at tough opponents Stuttgart last weekend will have revitalised the positive spirits.
Performances have been far from perfect with results tending to flatter Leverkusen so far, but this at least highlights the clinical trait Seoane's side have picked up in the early stages of the new campaign.
Die Werkself raced into a 2-0 lead in Stuttgart last weekend but with Robert Andrich seeing a straight red card just 31 minutes in, and their opponents pulling a goal back shortly after, they had to grind out the impressive result.
Youngster Florian Wirtz was the star of the show and added a third in the second half to give his side a fairly comfortable finish to the match.
As for the visitors, they find themselves sitting just one place behind their weekend's opponents, after achieving an identical record in the league so far.
However, the difference for Mainz is that they are expected to compete at the opposite end of the Bundesliga table, unlike their hosts.
Manager Bo Svensson has continued his side's miraculous turnaround last campaign into the new season, where his record is nothing short of remarkable for a club usually fighting off relegation.
Wins over RB Leipzig, Greuther Furth and Hoffenheim have all been achieved without conceding a goal, and adding in last weekend's goalless draw at home to Freiburg, Die Nullfunfer boast the equal-best defensive record in the division.
Therefore, it is clear that Svensson has built his side on a strong defensive foundation, with solidarity taking priority over creativity and goals scored.
As a result, the same will be expected on Saturday when they visit a tough opponent that has inflicted six defeats on them in their past seven meetings.
Bayer Leverkusen Bundesliga form:
Bayer Leverkusen form (all competitions):
Mainz 05 Bundesliga form:
Mainz 05 form (all competitions):
Team News
Hosts Leverkusen will be sweating over the fitness of top goalscorer Patrik Schick for Saturday, with the striker taking a heavy knock in Stuttgart last weekend.
Lucas Alario has made his return from injury in the last couple of weeks so will be waiting to pounce on the opportunity should Schick fail to shake it off.
After his red card last time out, Andrich is suspended for the visit of Mainz, with Kerem Demirbay expected to replace him in the centre of midfield.
Along with Andrich, Timothy Fosu-Mensah, Edmond Tapsoba, Exequiel Palacios and Julian Baumgartlinger are all missing too.
Meanwhile, Mainz continue to miss captain Moussa Niakhate due to a calf injury. Alexander Hack will continue in his absence in the visitors' defence.
Key striker Adam Szalai was substituted at half time against Freiburg last week due to a knee injury, so Karim Onisiwo should come into the starting lineup in his place.
Full-back Aaron Caricol remains the other expected absentee for Saturday, as he is still listed as a doubt due to a groin injury.
Bayer Leverkusen possible starting lineup:
Hradecky; Frimpong, Kossounou, Tah, Bakker; Demirbay, Aranguiz; Bellarabi, Wirtz, Diaby; Schick
Mainz 05 possible starting lineup:
Zentner; St Juste, Bell, Hack; Widmer, Barreiro, Kohr, Boetius; Lucoqui; Onisiwo, Burkardt
We say: Bayer Leverkusen 2-1 Mainz 05
Leverkusen will be hoping their clinical finishing can come to their assistance against a stubborn and well-drilled Mainz side on Saturday. It could be a tight affair but the hosts should possess enough quality to see off the visitors eventually, particularly with the likes of Diaby, Wirtz and Schick at their disposal.