The Liquigas-Cannondale team lead the chase for much of the stage, perhaps in the hope setting up an attack on the twisting descent to Tirano by Vincenzo Nibali. Contador was given an armchair ride to the finish but insisted it had not been an easy day in the saddle.
"It was a hard stage and very fast with an average of 48km/h in the first hour," he said after collecting his latest maglia rosa from British fashion designer Sir Paul Smith.
"Fortunately my training for the Giro was aimed to get me ready for huge efforts and long hard stages like this. The break got away but it was kept under by Liquigas and Geox because Nibali's and Menchov's GC positions were at risk. That played in our favour."
Contador's overall race lead remained unchanged. Michele Scarponi (Lampre-ISD) is second at 4:58 and Nibali is third at 5:45.
"I'm happy that we've covered another day of racing and that we're one day closer to the finish in Milan," he said.
"I've just got to be careful and everything will be okay. The stage over the Colle delle Finestre will be the last chance for Scarponi and Nibali to try something. I've got a lot of respect for them, but I know I can count on the help of other riders. I'm not worried."
Possible protest on Saturday
There is a slight risk that protesters against a high-speed rail link through the Alps could try and block the Giro d'Italia during Saturday's stage to Sestriere. That would help Contador, just as the cutting of the Crostis climb helped him earlier in the race.
He was always against the racing on the Crostis but claimed he wants to race on the dirt fire track that makes up the second half of the Colle delle Finestre.
"It'd be a real pity if we can't ride the Finestre. It's part of the stage route and it'd be right to do it. I hope we can do it for the fans and for the good of the sport," he said.