Ali's contested 3-pointer with 14 seconds left and the shot clocking winding down gave Portland an 86-82 lead to seal it.
Ali finished two points short of his career high set in an 86-73 win against Portland State on Saturday. Portland (4-1) has won four straight.
The Pilots weren't even given an exemption from the state of Oregon and Oregon Health Authority to hold full contact practice until Sunday, Nov. 22, just three days before the season officially started.
Oregon State (2-3) has dropped three straight by a combined total of eight points.
Portland led 36-29 at halftime before Oregon State emerged from the break with a 13-5 run for a 42-41 lead.
Ethan Thompson made a pair of foul shots for the Beavers with 6:31 remaining in regulation and Oregon State led 60-52. The Pilots countered and proceeded to outscore Oregon State 19-11 down the stretch and tied it at 71 when Isiah Dasher made a 3-pointer with 41 seconds to go. Both teams missed shots in the final seconds to force overtime.
Portland never trailed in overtime.
Thompson led the Beavers with a career-high 31 points.
Despite a 7-61 record in the West Coast Conference in the last four years, Portland coach Terry Porter moved his record to 2-0 against the Pac-12 Conference Beavers.
It was the first game in four years between the two schools. The Pilots beat Oregon State 53-45 on Dec. 18, 2016 at the Moda Center in Portland.
The win was just the fifth ever for Portland in Corvallis, Oregon.
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