While the hosts are bidding to win their first-ever Bundesliga title this season, the visitors are struggling at the wrong end of the table and are seeking to preserve their top-flight status for a 16th consecutive season.
Match preview
Bayer Leverkusen extended their exceptional unbeaten record across all competitions to 32 matches when they battled past Heidenheim 2-1 at Voith-Arena last weekend - equalling Bayern Munich's all-time German football record for the longest unbeaten streak from 2020.
Jeremie Frimpong's opener in first-half stoppage time was followed by an 81st-minute strike from Amine Adli to put Leverkusen two goals to the good; Tim Kleindienst pulled one back five minutes later to set up a nervy finish, but the visitors held on for their 18th league win of the campaign.
In-demand head coach Xabi Alonso, who has been linked with both Bayern and Liverpool in recent weeks, has seen his Leverkusen side extend their lead at the Bundesliga summit to eight points, which could be increased to 11 if they beat Mainz on Friday before Bayern play host to RB Leipzig on Saturday.
No Bundesliga team have failed to clinch the title having previously boasted an eight-point lead at this stage of the season, so Die Werkself should be confident of getting the job done in their remaining 12 games, starting with success against a Mainz outfit whom they beat 3-0 earlier this season.
Leverkusen will welcome a return to the BayArena where they have not lost any of their last 18 games in all tournaments, including 11 in the Bundesliga this season, although they did suffer a surprise 3-2 defeat the last time they played host to Mainz in February last year.
Mainz's 11-game winless run in the Bundesliga was brought to an end when they claimed a narrow 1-0 home victory over Augsburg last weekend - just the second time they have claimed maximum points this season.
The 05ers are the lowest scorers in the German top flight (17) this term, but they have made the net ripple in each of their last three matches, with defender Sepp van den Berg heading home the decisive goal shortly before half time against Augsburg, who had Mads Pedersen sent off for a late challenge deep into second-half stoppage time.
Bo Henriksen celebrated his first game in charge of Mainz with a crucial victory, which has seen the club move to within one point of 16th-placed Koln in the relegation playoff position and seven points behind Borussia Monchengladbach, who are hovering just above the drop zone in 15th spot and face the 05ers in a potentially pivotal fixture at the beginning of next month.
Mainz, who have 12 games left to play to close to gap to safety, are now gearing up for two daunting trips to Leverkusen and Bayern in their next two away games, and their form on the road has been miserable to say the least; the 05ers last won a Bundesliga away match in April last year and are the only remaining top-flight team who are yet to celebrate success on their travels this season (D6, L5).
There is reason for Henriksen and co to be optimistic of claiming a positive result on Friday, though, considering Mainz have won two of their last four meetings with Leverkusen, while they have picked up four points across their last three visits to the BayArena.
Bayer Leverkusen Bundesliga form:
W
W
D
W
W
W
Bayer Leverkusen form (all competitions):
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D
W
W
W
W
Mainz 05 Bundesliga form:
D
L
L
D
L
W
Team News
Bayer Leverkusen are still having to cope without top scorer Victor Boniface (groin), Exequiel Palacios and Arthur (both thigh) as they continue to recover from injury.
After returning to the matchday squad last weekend as an Africa Cup of Nations champion with Ivory Coast, Odilon Kossounou will be pushing to start as either a centre-back or midfielder on Friday, while Edmond Tapsoba, another who has recently returned from AFCON duty, could be recalled in defence.
Adli has scored in two of his last three appearances and should fend off competition from Jonas Hofmann and Nathan Tella to start again in the final third alongside Florian Wirtz and either Patrik Schick or Borja Iglesias.
As for Mainz, Andreas Hanche-Olsen (thigh), Nelson Weiper (knee) and Stefan Bell (illness) all remain in the treatment room, while Edmilson Fernandes (ankle), Maxim Leitsch (muscle) and Jonathan Burkardt (illness) are all doubtful and will be assessed ahead of kickoff.
The absence of Hanche-Olsen, who was forced off in the win over Augsburg, could see either Joshua Guilavogui or Anthony Caci start in the back three alongside Van den Berg and Dominik Kohr, while the other operates as a left wing-back.
After scoring 10 Bundesliga goals last season, Karim Onisiwo is yet to find the net is 17 appearances so far this season, but the Austrian is expected to continue in attack alongside Brajan Gruda and Lee Jae-sung.
Bayer Leverkusen possible starting lineup:
Hradecky; Stanisic, Tah, Hincapie; Frimpong, Xhaka, Andrich, Grimaldo; Adli, Wirtz; Schick
Mainz 05 possible starting lineup:
Zentner; Kohr, Van den Berg, Guilavogui; Mwene, Barreiro, Amiri, Caci; Gruda, Onisiwo, Lee
We say: Bayer Leverkusen 3-1 Mainz 05
Both team will be determined to claim all three points for different reasons, and although Mainz celebrated success at the BayArena last season, there is no hiding the fact that Leverkusen enter Friday's contest as firm favourites to come out on top.
Alonso and co have shown that they still boast an attacking threat even without the presence of Boniface, and they should ultimately have few problems breaching Mainz's backline en route to claiming a title-boosting victory.