Briscoe took over the lead when Power, the pole-sitter, pitted for final time during the closing laps, then made his own last pit stop when the caution flags came out for an accident involving Sebastien Bourdais and rookie Josef Newgarden.
Briscoe came out ahead of his teammate when Power got caught up in traffic during the restart and went on to claim his first IndyCar win since June 2010 at Texas, finishing 0.44 seconds in front.
Power came in second but emerged the big winner at Sonoma by extending his IZOD Series points lead over Ryan Hunter-Reay to 36 following the latter's 18th-place finish.
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