Going into the key individual time trial stage in Folsom, there was a question mark over whether the Frenchman could do enough to keep the likes of noted time triallists Rohan Dennis (BMC) and Andrew Talansky (Cannondale) at bay.
The short, flat 20.3-kilometre route threw up some very fast times from the off, with British rider Owain Doull (Team Wiggins) and American Taylor Phinney (BMC Racing) two riders to spend an extended time in the hot seat.
In fact, Phinney’s time was only eventually bettered by stage winner Dennis and Talansky. However, no rider could do enough to overthrow Alaphilippe who finished the stage in eighth spot to retain the race lead.
Disaster struck former Tour of California winner and time trial world champion Bradley Wiggins (Team Wiggins) when one of his aerobar extensions came off, and he rolled to the finish.
Alaphilippe and his Etixx-QuickStep team must now navigate the final hilly stage on Saturday to ensure that the win is secured in Sacramento on Sunday. They will be most wary of the massed ranks of BMC Racing, whose Dennis and Brent Bookwalter are within 16 and 38 seconds of Alaphilippe respectively.