Tejay Van Garderen tightened his grip on the yellow jersey at the USA Pro Challenge with victory on the stage five time trial.
The American (BMC Racing) blasted through the intermediate split time quickest of anyone before going on to set a Vail course record time of 25mins 1sec, four seconds quicker than Andrew Talansky (Garmin-Sharp).
That result pushed Van Garderen's lead out to 1:30 over team-mate Mathias Frank with two stages to go. Third on the day and in the same place overall, Tom Danielson (Garmin-Sharp) sits a further 12 seconds back.
Kanstantsin Siutsou clocked the seventh fastest time over the 16.1-kilometre course to put in the best time for Team Sky on the stage five.
The Belarusian national champion set a strong early benchmark of 26 minutes and 17 seconds over and saw his time stand up well during the day.
With rain forecast for the later runners there had been some nervous looks to the sky, yet the sun continued to shine on Colorado during a decisive day of the race.
With tough ramps heading into the final 5km the course provided a perfect chance for riders looking to land a blow in the fight for the general classification.
After Richie Porte and Chris Froome had set early times Siutsou went through the intermediate split fastest, clocking a new best effort before Talansky quickly moved the bar along, 1:12 quicker.
Steve Cummings (BMC Racing) was Talansky's nearest challenger for a spell before ending the day a fine fourth, yet Van Garderen proved to be unstoppable as he put himself in the box seat heading into the weekend.