TROYES, France (AP) Dancing on his pedals and accelerating up the mountain past Chris Froome and all of the other Tour de France favorites, Fabio Aru's audacious attack brought back memories of Lance Armstrong's one-time challenger, the late Marco Pantani.
It was the work of a ''pure climber,'' as Giuseppe Martinelli, Aru's team director who guided Pantani to the 1998 Tour title, put it.
''The way Fabio attacks reminds me of Pantani,'' Martinelli said in an interview with The Associated Press. ''Yesterday's attack was just like one of Pantani's moves.
''Besides making the other guys hurt, he also created a gap. And he's got the courage to try,'' added Martinelli, who has coached Pantani, Stefano Garzelli, Gilberto Simoni, Damiano Cungeo, Vincenzo Nibali and Aru to a total of nine Grand Tour victories.
The Stage 5 victory Wednesday at the Planches des Belles Filles ski station in eastern France's Vosges mountains was where Nibali set up his 2014 Tour title, becoming the only rider to break Froome's hegemony over cycling's biggest event amid the British rider's wins in 2013, 2015 and 2016.
While Aru is not as complete as Nibali, he seems to have an extra gear in the mountains.
''Lately, a lot of climbers attack only when they're sure they can reach the finish, with 500 meters or a kilometer to go,'' Martinelli said. ''Aru attacked with 2.5 kilometers remaining on a 5-kilometer climb. On a 10-kilometer climb he could be capable of attacking with 5K to go.''
Whatever he's capable of, one thing is for sure: Aru - his name is pronounced with the accent on the first A - has all of a sudden become a serious threat to Froome, the yellow jersey holder.
With more climbing on the route this weekend, especially Sunday's stage to Chambery in the Alps, which includes three beyond-category ascents, Aru will be looking to improve on his third-place position in the standings and erase his 14-second deficit to Froome.
''Chris is very strong but I remember battling with him since the 2014 Vuelta,'' said Aru, who won the Spanish Vuelta in 2015. ''I respect him but I've never been afraid to attack him. It will be a battle until the end. ... When I have strength I'll attack.''
At 1.83 meters (6 feet) and 66 kilograms (145 pounds), Aru has just the right power-to-weight ratio to be a threat when the road tilts upward.
Pantani had a similar build but his career was derailed by doping cases and he died of cocaine poisoning in 2004.
So is Aru clean?
''He shows it every day. Cycling is clean now,'' Martinelli said. ''I've got a son who is a pro and I know that 99.9 percent of the riders racing now are clean.''
The big question for Aru is whether he has the stamina to keep up with Froome and other contenders like Richie Porte in stages with multiple climbs.
Froome said he let Aru go because he still had two Team Sky members protecting him and knew Aru was far back in the standings.
''In hindsight, I could have done things differently but certainly going forward I'm not going to watch him ride away,'' Froome said.
Aru had opened the season aiming to win the Giro d'Italia, which started in his home region of Sardinia. But a knee injury forced him to sit out and focus on the Tour instead.
Aru also struggled last year, cracking in the penultimate stage of his Tour debut.
His victory in the Italian championship a week before the Tour was his first win in more than a year.
''I went through some really dark times and only those close to me can really appreciate how difficult it was,'' Aru said.
Aru's national championship win came while wearing the jersey of Astana teammate Michele Scarponi, who died after a collision with a van while training in April. After the Tour, Aru plans to give the jersey to Scarponi's widow.
In the meantime, Aru has traded his green, white and red national champion jersey for the polka-dot king of the mountains shirt.
No matter which jersey Aru has on, he always wears a helmet and sunglass frames featuring a design of the Sardinian flag with its four Moors. He signs all of his tweets with the hashtag of ''ilcavalieredei4mori'' - the knight of the four Moors.
''He's really proud to be Sardinian,'' Martinelli said. ''When he won the Vuelta he took a Sardinian flag - not an Italian flag - up with him to the podium celebration in Madrid.''
Aru is the only pro rider from the Mediterranean island of Sardinia. He's now based in Lugano, Switzerland.
''He had to leave his family when he was 16 and move north to train,'' Martinelli said. ''His is a very Italian story in that he had to emigrate to find success. It didn't all come easy for him.''
Aru has also had two podium finishes in the Giro and at 27 remains relatively young for a Grand Tour contender. Still without a contract for next season, he's a prized commodity.
''Usually when (Astana team manager Alexandre) Vinokourov wants to keep something he does,'' Martinelli said. ''I'm confident he'll remain here.''
Andrew Dampf on Twitter: www.twitter.com/asdampf