CLOVIS, Calif. -- Slovakia's Peter Sagan raced to his event-opening fourth straight stage victory in the Tour of California on Wednesday to increase his overall lead to 16 seconds.
The 22-year-old Sagan, riding for Liquigas-Cannondale, finished the 130.2-mile stage from Sonora to Clovis -- the longest leg in the race -- in 5 hours, 18 minutes, 8 seconds in temperatures that reached 95 degrees.
"Today was a harder stage," Sagan said. "Today, I was thinking it was not possible for me to win, but (teammate) Daniel (Oss) said, 'Today we work for you.' "
Australia's Heinrich Haussler, racing for Garmin-Barracuda, was second for the fourth straight day, about a bike-length behind. Rabobank's Michael Matthews, also from Australia, was third in the stage.
Jeff Louder, the United Healthcare rider from Salt Lake City, was 34 seconds back in third place with four stages left.
Sagan's fourth straight 10-second bonus for a stage win gave him a 40-second advantage over the expected overall contenders, including defending champion Chris Horner, the RadioShack-Nissan rider from Bend, Ore.
Horner finished in the main field for the fourth consecutive day. He was 27th in the stage and 18th overall.
Three-time race winner Levi Leipheimer of Santa Rosa, Calif., who rides for the Belgium-based Omega Pharma-QuickStep team, was 36th overall, also 40 seconds back.
"I think tomorrow I will say goodbye to the yellow jersey," Sagan said. "But maybe tomorrow I recover and try for another stage later in the race."
Haussler, a former Tour de France stage winner, again failed in an attempt to pass Sagan in the final sprint.
"Sagan is the fastest guy at the moment, and he proved it again today," Haussler said. "I believe we've got one more opportunity for a sprint. And I'm very motivated, but there's some serious racing to get through in the next few days."
The warm conditions led four riders to abandon the race, with 118 from a starting field of 128 in Santa Rosa now left.
The eight-day event continues Thursday with an 18.4-mile individual time trial in Bakersfield, followed by two mountain stages. The 735-mile race concludes Sunday with a 42-mile road race from Beverly Hills to Los Angeles.