Alexander Vinokourov of the Astana team retained the overall leader's pink jersey after the top riders all finished reasonably close together in the central Italian hills.
The Kazakh, who overcame appalling conditions on Saturday to take the lead, holds a one minute 12 second advantage over Australian world champion Cadel Evans with previous race leader Vincenzo Nibali edging back up to the third overall.
Vinokourov returned to cycling last year after a doping ban but lost none of his grit and determination during his time away and now looks favorite to lift the title in Verona on May 30 after three tough weeks of racing.
Saxo Bank's Sorensen, who broke his collarbone during the Tour of Catalunya in late March, triumphed on a 189-km ride from Chianciano ahead of Italian revelation Simone Stortoni of the Colnago CSF Inox team. Spain's Xavier Tondo was third for Cervelo.
"The situation was completely insane. On the last three kilometers I am in the car with goosebumps all over my body and inches away from being a nervous wreck screaming out the window, then screaming into the steering wheel while Pascal (mechanic) is hanging out the sun roof rooting for Chris (Anker Sorensen)," Saxo Bank sports director Dan Frost said in a team statement.
"His fight in the front of the race is an image of the way our whole team has been fighting for success in this race. They are all putting in everything they have to succeed as a rider and as a team.
"The only difference is that today the struggle was visible to everyone. We came to the Giro with no big expectations and this delegation of riders simply keeps surprising us all and they have now made the Giro a success for the team." No Italian has won a non-team stage yet in this year's race and the chance of a home victory on Monday's 187-km flat route from Frosinone to Cava de' Tirenni south of Naples has been hit by Alessandro Petacchi's retirement.
The Lampre sprinter pulled out early on in the stage because of bronchitis.
