Daniel Caligiuri's stunning individual goal helped Schalke maintain their grip on second in the Bundesliga with a 1-0 win against Mainz.The 30-year-old midfielder picked the ball up near the halfway line and dribbled past two players before firing into the top right corner from 20 yards.And his second-half strike proved pivotal as the visitors recorded a fourth straight win that moves them four points clear of third-placed Borussia Dortmund.Mainz remain third bottom after their three-match unbeaten run was ended, but they caused Schalke problems.Robin Quaison struck a post in the first half while Daniel Brosinski shot wide early in the second.After Caligiuri's moment of magic in the 55th minute, the hosts pressed for an equaliser.Suat Serdar saw a couple of long-range efforts saved by Schalke goalkeeper Ralf Fahrmann while Alexandru Maxim's effort was blocked by a diving Nabil Bentaleb.With time running out, Fahrmann parried clear a shot from Levin Oztunali, who then flashed a ball across goal as Schalke held on.