After finishing second in the first three stages, Sagan — the Tinkoff-Saxo rider who has four
"I never looked back," Sagan said. "I was just in the group, and I trust my teammate. He bring me on the front for the last corner left."
Skujins, the American Hincapie Sportswear rider who won the third stage, had a 22-second lead over Sagan after finishing 67th in the main field. Sagan gained 10 bonus seconds for the stage win.
"It was pretty big for us," Skujins said. "It was pretty hard because it was windy, but we kept it in check, and Quick-Step did a lot of work for us, which was awesome. It worked out for us, so all is well. "We'll see what happens with the time trial and the weather."
Rain is predicted for Stage 5 and current snow in Big Bear Lake may force the relocation of the Stage 6 individual time trial for the men's field and the women's invitational time trial scheduled the same day.
Canada's Rob Britton of SmartStop, remained third overall— 43 seconds back.
Drapac rider Wouter Wippert of the Netherlands was second in the stage, about two bike-lengths behind. Britain's
Sagan came around the final corner in sixth position, but he made his sudden move with about 150 meters left and swiftly passed Italian
"Mark Cavendish was behind me, maybe I did some turns better," said Sagan, who did two small "wheelies" as he crossed the line. "And from the last corner I just sprinted. I'm very happy."
Sagan, who had not won a race since March 16, claimed 10 races last year. He was criticized by his team owner earlier this season.
An early stage breakaway group of five built as much as a 3:10 advantage. The main field steadily narrowed it deficit to 45 seconds with about 20 miles left.
American Greg Daniel bolted into a solo breakaway and stretched his margin to 30 seconds with about 12 miles left. But the main field, which earlier caught the rest of the breakaway leaders, absorbed Daniel three miles later.