The American made 46 unforced errors as she struggled to keep the ball in the Arthur Ashe showcourt on a steamy New York morning.
Vento-Kabchi, ranked a lowly 84th in the world, simply kept the ball in court as Rubin all but beat herself.
Earlier on day one of the $17.1 million Grand Slam, Ashley Harkleroad gave home something to cheer about by racking up her first U.S Open match victory.
The teenager thumped Russian Vera Douchevina 6-4, 6-2 in just 65 minutes.
