The Huskies (4-0, 1-0 Pac-12) had a hard time shaking Arizona (2-2, 0-1), which was down to its fourth-string running back after J.J. Taylor suffered what coach Rich Rodriguez said was a broken left ankle.
Washington had the ball first in overtime and Pettis made a tough grab in traffic. Washington's defense then forced a turnover on downs to eke out the harder-than-it-should-be victory.
"We can do better than that," Washington coach Chris Petersen said.
Brandon Dawkins kept the Wildcats in it, dazzling with 176 yards and two touchdowns rushing, 167 yards and another score passing. He escaped what appeared to be a sack to hit Shun Brown on a 54-yard pass , then foundJosh Kern on a 3-yard TD pass with 17 seconds left to tie the game at 28.
Dawkins couldn't come through in overtime, though, unable to find a receiver on the final play after scrambling to grab a bad snap.
"We had some mistakes that cost us against a good team; they're a really good team," Rodriguez said. "We've just got to get some execution things cleaned up in all three phases and try to get better."
Coleman kept the Huskies moving with Browning limited to passes underneath and scored on a 55-yard touchdown run in the fourth quarter. Browning finished 14 of 21 for 160 yards and two touchdowns.
Washington: The Huskies faced adversity for the first time after three easy wins to open the season and survived. Washington failed to capitalize after manhandling the smaller Wildcats to start the second half - a 171-12 advantage in total yards - yet made the plays when it needed to down the stretch.
Arizona: The Wildcats' quick-tempo offense went into a slumber for a long stretch of the second half and its defense was manhandled at times by the Huskies. Arizona had a shot at the end and failed, but the bigger concern is depth after seeing another running back go down.
"Just unbelievable," Rodriguez said of the injuries.
Washington: The Huskies host No. 7 Stanford next Friday in what should be just the fourth game ever between top-10 teams at Husky Stadium.