Kazakhstan's Alexandre Vinokourov retained the overall leader's pink jersey.
Farrar, 25, beat home Italian Fabio Sabatini while the American's team-mate Julian Dean of New Zealand was third, after doing excellent lead-out work for the stage winner, while Australian veteran Robbie McEwen was fourth.
Three riders, France's Hubert Dupont, British rider Charles Wegelius and Dario Cataldo of Italy had tried to liven up the stage earlier in a long escape before being reeled in 16km from the finish.
Wednesday's 11th stage is at 262km the longest of this year's edition from Lucera to l'Aquila.
In Santa Rosa, California, Australian Brett Lancaster accelerated to the front of a group of 26 riders over the final meters to claim stage two and assume the race lead in the rainy Tour of California on Monday.
Lancaster, a 2004 Olympic team pursuit gold medalist, claimed the 177.2-km (110.1-mile) Davis to Santa Rosa stage in a provisional time of 4 hours 38 minutes 35 seconds.
Peter Sagan of Slovakia finished second with Lars Boom of the Netherlands third, both in the same time as the winner.
A former Tour of Italy prologue winner, Lancaster began stage two trailing former race leader Mark Cavendish of Britain, who did not finish in the lead group, by 10 seconds.
With his 10-second stage win time bonus, Lancaster now leads the eight-day event by four seconds from Sagan.
American Levi Leipheimer, looking to win the race for the fourth time in succession, and teammate Lance Armstrong, the seven-times Tour de France winner, finished among the lead group of 26.
An initial lead group of five riders was joined by a group of 21 other cyclists about 153 kilometers into the overcast and rainy stage. The leaders quickly expanded their margin and the main field was split into several groups.
The race continues on Tuesday with a 182.3-km (113.3-mile) stage from San Francisco to Santa Cruz.
