Victory moves Schalke four points clear of third-placed Borussia Dortmund.

Mainz, playing its 400th game in the Bundesliga, dominated the first half at the Opel Arena but was unable to find a way past goalkeeper Ralf Fahrmann.

Schalke earned the points thanks to Caliguri's brilliant 55th minute intervention, the midfielder skipping away from three defenders before thumping a 25-yard drive into Florian Muller's top-left corner.

Although Fahrmann had to beat away a fine effort from Suat Serdar, a fourth straight win for Domenico Tedesco's side means Schalke now has a five-point cushion in the race for top-four places in the Bundesliga.