Mike Rouse singled to lead off the frame, advanced to second on a sacrifice bunt by Joe Inglett and slid in just ahead of Brett Gardner's throw home on Rivas' base hit up the middle.
Ben Francisco and Andy Marte each ripped a solo homer for the Bisons (72-62), who moved to within a game of International League Wild Card-leading Richmond.
Bubbie Buzachero (4-6) picked up the win despite allowing two runs on four hits in two frames, and Mike Koplove tossed a perfect ninth to pick up his 13th save. Bisons starter Jason Stanford yielded one run on three hits and struck out five in three innings.
Yankees reliever T.J. Beam (4-3) suffered the loss, surrendering one run and two hits in 1 1/3 frames, and starter Kei Igawa allowed three runs, five hits and a walk while fanning three in 6 2/3 innings.Eric Duncan drove in two runs with a double in the seventh and Jose Cruz Jr. scored twice and hit his first homer, a solo blast, in the first for the Yankees (76-58), who have lost three in a row