Vincenzo Nibali: I'm at the Tour de France to work for Fabio Aru

After losing over eight minutes to the general classification contenders on the difficult finale to the Tour de France's fifth stage, 2014 winner Vincenzo Nibali says it's all normal, insisting he's there to work for Astana teammate Fabio Aru.

With one eye on the Olympic road race in Rio in August, Nibali, who took overall victory at this year's Giro d'Italia, looked to be far from putting in his full effort on the Pas de Peyrol climb around 35km from the finish where he was dropped by the likes of Chris Froome (Team Sky), Nairo Quintana (Movistar) and Alberto Contador (Tinkoff).

Despite his team management not ruling out a GC place for the 31-year-old at this year's Tour, Nibali says it has always been the plan to support Aru and that he just didn't have the legs on the climbs.

“I haven’t had my best day..." Nibali explained, "honestly I didn't know how my legs could have answered to the high rhythm in the climbs.

"Probably I also suffered a little bit for the first hot temperatures in this Tour, but I’m relaxed because, as we have said in the last two weeks, we are here to help Fabio Aru to gain the best result possible.

Watch: Tour de France stage five highlights

"I’m sure my condition will grow in the next days and I will be ready to stay close to Fabio soon."

Having had only 15 days rest after his Giro victory in May, Nibali is expected to build towards leading the Italian squad in Rio on August 6.

But even Astana general manager Alexandre Vinokourov admitted Nibali suffered somewhat of a "crisis" on Thursday after finishing over 13 minutes down on stage winner Greg Van Avermaet.

Defending Tour champion Froome also said he was surprised and had expected Nibali "to come here with his A game".

"He [Nibali] was in a bit of a crisis today," Reuters report Vinokourov as saying.

"But the most important thing is that Fabio is here (with the best)."

"We were saying at the beginning that we did not have any indication on his form, apparently he has not recuperated from the Giro."

Nibali had targeted defending his Tour title in 2015, but also suffered then in the wake of Froome and Quintana on the climbs. Despite losing a significant amount of time, the Sicilian was able to recover in third week to win stage 19's summit finish to La Toussuire in the Alps, as well as secure fourth place overall.

He currently sits in 50th place overall, 14-06 back on race leader Van Avermaet, as the race heads towards the Pyrenees and a finish on the Col d'Aspin on Friday.