Yunus Malli gave the German side the lead after ten minutes from the penalty spot, however Łukasz Teodorczyk scored a second half equaliser for the Belgians.
Both sides are level on five points with AS Saint-Étienne as a result, after the French side won 1-0 against FK Gabala.
Mainz looking to build on solid start
Mainz were looking to build on their four points won in the group so far, having secured their first ever victory in the Europa League against Gabala three weeks ago. They also returned to winning ways in the Bundesliga after the international break on Sunday, beating SV Darmstadt 98 2-1.
There were three changes from the side that started that game, with Niko Bungert, Suat Serdar and Karim Onisiwo replacing Alexander Hack, Daniel Brosinski and Levin Öztunali.
Likewise Anderlecht had four points after victory against Gabala before drawing with Saint-Étienne last time out. They are currently top of the Pro League in Belgium, warming up for this game with a 1-0 win over Sporting Lokeren.
Olivier Deschacht and Emmanuel Sowah came into the side that started that league match, with the injured Uros Spajic out and Massimo Bruno, on loan from RB Leipzig, dropping to the bench.
Malli spot kick makes the difference
Mainz started on the front foot, and after nine minutes they received a penalty, with the veteran Deschacht bringing down Pablo De Blasis in the box. Malli chipped the ball well over Davy Roef to give the home side the lead.
Although Mainz dominated, Anderlecht still proved dangerous, with Sofiane Hanni twice forcing Jonas Lössl into important saves. The first effort was an impressive turn-and-shoot from the Anderlecht skipper, whilst the second came from a quick break, with Hanni found by an excellent ball by Teodorczyk.
Onisiwo was particularly dangerous down Mainz’s right, and he came closest to a second goal with a curling shot scrapping the post on its way wide.
Otherwise they didn’t quite threaten the target, with De Blasis shooting wide, before two more chances just before the break. Jhon Córdoba couldn’t quite connect with a Malli cross, before De Blasis headed a Giulio Donati cross wide, with a slight deflection off Sowah.
Teodorczyk saves point for Anderlecht
Mainz started brightly, with Córdoba finding De Blasis with an excellent cross. The Argentinean winger got the slightest of connections, however it was saved by an alert Roef.
Despite the constant rain affecting the quality of the pitch, neither side were afraid to get forward. Anderlecht struggled when they did though, with two great runs from Frank Acheampong and then Hanni both coming to little.
Eventually though they struck. Hanni turned from two Mainz defenders on the edge of the box, and his perfectly-placed cross was headed in by Teodorczyk to bring the game level.
Significant chances after that proved limited. Brosinski had his shot from outside of the box taken by Reof. And in stoppage time, Malli shot over the bar on the rebound from a Brosinski free-kick.
Mainz though will take a point against one of Europe’s established sides, even if they will feel like they could have taken more from this game. The two sides meet again in Brussels in two weeks’ time.