Cycling-Quintana snatches Giro lead from Dumoulin

May 26 (Reuters) - Nairo Quintana claimed the overall lead in the Giro d'Italia on Friday after Tom Dumoulin lost ground in the final ascent of an eventful 19th stage won by Spain's Mikel Landa. Quintana's Movistar team attacked 135km from the finish when Dumoulin (Team Sunweb) was at the back of the peloton, possibly because nature had called and the Dutchman could not follow in the 15.5-km climb up to Piancavallo. Frenchman Thibaut Pinot was the overall contender who gained most after he dropped Quintana and Italian Vincenzo Nibali (Bahrain-Merida) with about six kilometres left. Quintana now leads second-placed Dumoulin by 38 seconds, third-placed Nibali by 43 and Pinot (FDJ) by 53. Saturday's penultimate stage will feature two big climbs that could favour Nibali, Quintana and Pinot, while Sunday's final time trial, a 29.3-km effort, is expected to go Dumoulin's way. (Reporting by Julien Pretot; Editing by Hugh Lawson)