Italy's Andrea Noe, the oldest rider in the 2007 Giro d'Italia, took the overall race lead after the uphill finish to the Sanctuary at Nostra Signora della Guardia near Genoa.
Noe, 38, finished 10th on the 249-km stage, 52 seconds behind winner and compatriot Leonardo Piepoli, but previous leader Marco Pinotti was four minutes behind and so the Liquigas rider pulled on the pink jersey.
He leads compatriot Marzio Bruseghin by 1:08, with Spain's David Arroyo third at 1:15. Pinotti slipped to ninth overall, 3:11 behind Noe.
Noe has been a professional for 15 years but has only won four races. 'This is a like a lifetime achievement award,' an emotional Noe told reporters.
'I wore the pink jersey for a day nine years ago but I've always loyally worked for my team leaders and been happy to see them win.
'I've got the lead because my Liquigas team won the opening team time trial in Sardinia and then I gained three minutes on stage eight by being in a breakaway.
'We were hoping to take the jersey and win the stage with Danilo Di Luca, so it wasn't a perfect day, but it's a huge personal satisfaction,' The Italian added.
The stage along the twisting Italian coast was marked by an attack by five riders, including US champion George Hincapie. They opened a five-minute lead mid-way through the stage but were caught at the start of the 8.8-km climb to the finish.
Piepoli attacked four km from the finish and forced the overall contenders to show their hand.
Di Luca appeared to be the strongest and finished 18 seconds behind Piepoli, with Luxembourg's Andy Schleck third another nine seconds adrift.
Wednesday's 198-km 11th stage from Serravalle Scrivia to Pinerolo near Turin is the last chance of victory for the sprinters before the start of the decisive mountain stages in the Alps and Dolomites.
