Los Angeles - American Tejay Van Garderen seized the Tour of California overall lead on Wednesday with a victory in the 34.7km time-trial fourth stage in San Jose.
The 29-year-old BMC rider won the race against the clock in 40:47, finishing seven seconds in front of his team-mate Patrick Bevin of New Zealand. Britain's Tao Geoghegan Hart (Sky) was third, 32 seconds back.
Van Garderen, competing in California for the first time since winning the 2013 edition, posted his second stage win in the principal stage race on the US calendar.
He grabbed the leader's yellow jersey from Colombian Sky rider Egan Bernal, who had topped the overall standings since winning the second stage on Monday.
"Today was special motivation," said Van Garderen, whose family was on hand.
He said he had thought if he could stay within striking range on Monday's mountain finish on Gibraltar Road he'd get a shot at the yellow jersey in the time trial.
"I had memories of here from five years ago. I didn't expect it to go quite this well, but I kind of had in the back of my mind on Gibraltar that if I can keep it to within a minute I can maybe take it today.
"Today was going to be my big power play - I'm glad I was able to produce one."
Bernal finished 1:23 behind Van Garderen in finishing 18th in the time trial and now trails the American by 23 seconds overall.
Thursday's fifth stage, 176.5km between Stockton and Elk Grove appears set to belong to the sprinters, with little likely upset to the overall standings two days from Saturday's finish in the state capital of Sacramento.
"Right now I'm just soaking in the moment," Van Garderen said of his thoughts on maintaining his position.
"I think tomorrow and Sacramento should be sprint days, so we really just need to worry about that (mountain) stage into Tahoe.
"But we have a really strong team. Motivation is going to be high and if you want to beat me you're going to have to go to the bitter end."
Results and standings after Wednesday's fourth stage of the Tour of California, a 34.7km time-trial in San Jose:
1. Tejay Van Garderen (USA/BMC) 40min 47sec (avg speed 52.1 km/h), 2.
Patrick Bevin (NZL/BMC) at 7sec, 3. Tao Geoghegan Hart (GBR/TeamSky)
32, 4. Lawson Craddock (USA/EF-Drapac) 46, 5. Filippo Ganna
(ITA/TeamEmirates) 49, 6. Mikkel Bjerg (DEN/Hagens-Berman) 53, 7. Jack
Bauer (NZL/Mitchelton) 55, 8. Neilson Powless (USA/LottoNL) 56, 9.
Maciej Bodnar (POL/Bora) 57, 10. Daniel Martínez (COL/EF-Drapac) same
18. Egan Bernal (COL/TeamSky) 1:23
Overall standings after 4 of 7 stages
1. Tejay Van Garderen (USA/BMC) 12hr 50min 55sec, 2. Egan Bernal
(COL/TeamSky) at 23sec, 3. Daniel Martínez (COL/EF-Drapac) 37, 4. Tao
Geoghegan Hart (GBR/TeamSky) 52, 5. Adam Yates (GBR/Mitchelton) 1:07, 6.
Rafal Majka (POL/Bora) 1:29, 7. Brandon McNulty (USA/Rally) 2:08, 8.
Laurens De Plus (BEL/Quick-Step) 2:13, 9. Kristijan Ðurasek
(CRO/TeamEmirates) 2:15, 10. Brent Bookwalter (USA/BMC) 2:34