The Valencia-based club fell behind to an Alvaro Cejudo strike in the 39th minute and Nino netted a second for Pamplona-based Osasuna three minutes later.
Cejudo, who had already been booked for taking his shirt off in his goal celebration, was shown a second yellow card in the 59th minute but Levante were unable to exploit their numerical advantage and their astounding seven-match winning streak came to an end.
Big-spending Malaga climbed above Espanyol into sixth when they beat the Catalan capital's second club 2-1 at the Rosaleda.
Athletic Bilbao were held to a 1-1 draw at Sporting Gijon, Croatian substitute Mate Bilic grabbing an equaliser for the hosts after Markel Susaeta's 63rd-minute effort.
Atletico Madrid secured their first win in six games when Spain under-21 striker Adrian scored twice in a 3-1 success at home to Real Zaragoza, easing pressure on new coach Gregorio Manzano.
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