Tim Hoogland put the visitors ahead only after eight minutes but Leverkusen replied fiercely to take the lead 11 minutes later.

Michal Kadlec restored parity on the quarter-hour mark, before Tranquillo Barnetta put the home side in front on 19 minutes.

Toni Kroos notched another one for Leverkusen on 30 minutes.

Niko Bungert pulled one back for Mainz seven minutes past the hour mark but Eren Derdiyok restored the hosts' two-goal cushion two minutes from time.

Leverkusen are now two points ahead of Bayern Munich who lie second on 36 minutes.