After Johnson hit a jumper in the middle of the key with 2:36 remaining to make it 55-53, Dwight Powell answered on a baseline drive with 1:21 to go before Johnson delivered once more.
Johnson finished with 16 points, five rebounds and four assists for Arizona (21-0, 8-0 Pac-12 Conference), off to the program’s best start in conference play in more than a decade.
Powell had 13 points for Stanford (13-7, 4-4).
ARIZONA ST. 89, CAL 78 (OT)
Jahii Carson scored a game-high 29 points and recorded seven assists to carry Arizona State past Cal. Tyrone Wallace led Cal with 20 points. The Bears (14-7, 5-3) have now lost three in a row after opening Pac-12 play 5-0.
USF 84, Portland 71
Kruize Pinkins scored 20 points and grabbed seven rebounds as USF posted its third straight West Coast Conference win. Cole Dickerson had 21 points and five rebounds for the Dons (14-8, 7-3 WCC).
Gonzaga 54, Santa Clara 52
Sam Dower Jr. made a game-winning 3-pointer with 1.9 seconds left and finished with 12 points as Gonzaga avoided its first loss at Santa Clara since 2001.
— Staff, wire report