Warith Alatishe added 13 points and 11 rebounds for Oregon State (4-3), his second double-double of the season.
Khalid Thomas split a pair of free throws to give Portland State a 62-61 lead with 2:13 remaining. Rodrigue Andela made a layup for the Beavers with 24 seconds to play. Reichle and Alatishe each made two free throws to end it.
Ethan Thompson, who hasn't missed a start for the Beavers in 101 games, had just seven points on 2-of-11 shooting, snapping his 15-game streak scoring in double figures, dating to last season.
Portland State opened the second half on a 24-9 run to pull to 45-43, and then a 12-2 surge gave the Vikings their first lead, 58-57 with 4:00 remaining.
The Beavers beat Portland State 81-76 last season and lead the series 15-0.
Oregon State, which had Sunday's game against Southern California postponed due to COVID-19 issues within the Trojans' program, is scheduled to host Stanford on Dec. 31.
Portland State is scheduled to play at Eastern Washington on Dec. 31.
For more AP college basketball coverage: https://apnews.com/Collegebasketball and http://twitter.com/AP--Top25
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