Cycling - Dumoulin fends off Quintana to keep Giro lead

(Reuters) - Dutchman Tom Dumoulin took a massive step towards winning the Giro d'Italia when he fended off some desperate attacks by Nairo Quintana on stage 18 to retain the Maglia Rosa on Thursday.

While American Tejay van Garderen took his first ever Grand Tour stage win by edging out fellow day-long breakaway member Mikel Landa at the finish in Ortisei, back down the road the battle for the overall race lead was brewing.

The Dolomite climbs looked tailor-made for Movistar's Quintana but, try as he could, he failed to make any of his attacks stick and Dumoulin even threatened to extend his lead when he poured on the power on the final ascent.

Home favourite Vincenzo Nibali also tried to break Dumoulin but he never looked threatened.

Sunweb's Dumoulin and Quintana crossed the line in the same time and with two days of climbing left Dumoulin, leading by 31 seconds, now looks favourite to win the Giro.

A confident-looking Dumoulin cheekily asked Colombian Quintana "why you don't ride?" as they got off their bikes at the finish area - having expected a much stronger attack from his main rival over the day's five categorised climbs.

Nibali is one minute 12 seconds behind while Thibaut Pinot of France is still in contention after moving into fourth overall, one minute and 36 seconds back.

Van Garderen (BMC) produced a great finish to deny Spaniard Landa, who had looked like taking the stage for Team Sky.

"It's my first Grand Tour stage win and it feels incredible," the 28-year-old Van Garderen said.

The 100th Giro ends in Milan on Sunday.

(Reporting by Martyn Herman; editing by Mark Heinrich)