Nairo Quintana has not given up hope of claiming his second Giro d'Italia general classification victory, but he admits current leader Tom Dumoulin has no weaknesses.

The Movistar rider has been distanced in recent stages after Dumoulin surged clear on the individual time trial, and again atop Oropa on Saturday.

His advantage stands at two minutes and 41 seconds heading into the final week of the grand tour, with Dumoulin six stages away from his first major title.

Pre-race favourite Quintana could not keep up in the time trial, but more surprisingly he was also left behind on the uphill climax to stage 14 when Dumoulin extended his lead thanks to bonus seconds on the finish line.

A tough final week in the Alps beckons, which should suit Quintana, but he knows making enough time back to beat the impressive Dumoulin will not be easy.

"It's not a surprise for me to see him wearing pink, but rather how he's going…he's much stronger than expected," Quintana told a media conference on Monday's rest day.

"He's proving to have come to this race in excellent form, and up to this moment, we haven't seen any real weakness from him. He left all of us climbers behind on Oropa.

"[But] we're yet to see if he remains as consistent in the climbs coming up from Tuesday, which will be really long.

"Our hope is to see him fading a bit in this third week while we continue to grow. Theoretically, there are four or five riders who could win this Giro other than him, and these stages suit us really well."

Movistar team manager Eusebio Unzue has also been impressed by Dumoulin's form, comparing the 26-year-old with a five-time Tour de France champion.

"He reminds me of Miguel Indurain, with the time trials and his consistency," he said.

"He rides more on strategy than force, you saw that in the Vuelta [a Espana]. He's a difficult rival."