Harit found the bottom corner from the edge of the box with the outside of his foot on Friday to earn Schalke a victory which was scarcely deserved.

But that is unlikely to bother them as they reached 10 points from a third successive triumph.

Mainz remain in the play-off place with just three points from five games. Karim Onisiwo's equaliser from Suat Serdar's opener ultimately counted for nothing.

Leipzig visit Werder Bremen late on Saturday after fifth-placed champions Bayern Munich host Cologne.

Schalke's head of professional football Sascha Riether said it was a key win for his side.

"The victory was immensely important for us," he told broadcaster DAZN. "We're simply enjoying it."

Harit was the undoubted hero for Schalke as the 22-year-old Moroccan midfielder twinkled throughout and provided a cutting edge, otherwise lacking, in the last third.

After being involved in a fatal car crash last year, Harit struggled to impose himself in a struggling Schalke team but has now found top form.

"More focus, you have to change your way of thinking, training," he said of his transformation. "I changed everything and it's a payback for me.

"I'm very happy for the team, we have to continue (on) our way."

It was Harit's sublime pass that split the defence for Serdar's 36th-minute goal and his magic that created the late winner from nothing.

Mainz appeared to have the situation under control with Harit closed down as he moved in from the right wing.

However, half a metre of space proved enough as he curled his shot low beyond keeper Robin Zentner.

Mainz will rue a lost point they seemed to have secured 15 minutes from time when Onisiwo curled into the top corner after being left unattended in the box.

Coach Sandro Schwarz admitted to "very large" frustration at the defeat, having felt it was his side, rather than Schalke, who looked closer to a winning goal before Harit's decisive intervention.

Australian Associated Press