The 4-year-old son of Cryptoclearance entered the Classic with only two wins in seven starts this year. With jockey Jose Santos up, he sat behind the pace duel between Kentucky Derby winner War Emblem and E Dubai.
Turning for home, Santos put Volponi down on the rail and he hit another gear, winning off by 6 1/2 lengths. Medaglia d'Oro, who surged to the lead on the turn for home, held on for second, a neck ahead of Milwaukee Brew.
After setting the pace, E Dubai finished next-to-last and War Emblem, likely running his last race before heading for a breeding career in Japan, got home eighth.
"I think maybe he's just a tired horse," said Baffert, who all week before the race insisted War Emblem was well-rested, happy and ready to run.
Volponi has raced on both the main track and the turf this year on the east coast. In his last start, just three weeks ago, he rushed from well back to finish a close second behind Burning Roma in the Meadowlands Cup Handicap. His last victory was in the 1-mile Poker Handicap on the turf at Belmont Park on July 2.
Hall of Fame trainer Philip Johnson said he added blinkers to Volponi's equipment after the Meadowlands race because he felt he had been too far behind in that event. He said he originally blamed the jockey, but after watching a tape of the race concluded it was a matter of the horse's field of vision.
"The blinkers make him concentrate a little bit," Johnson said.
Johnson bought Volponi's Dam, Prom Knight, for $8,000, let her run one race, in which she was injured, and then bred her as a 3-year-old.
When Volponi was born, he sold a half stake to his partner, Edward Baier, for $75,000.
"He probably would have brought $200,000 at Keeneland but I loved that horse," Johnson said.
Despite his recent troubles, Volponi won stakes races at ages 2, 3 and 4.
Johnson, a long-time Chicagoan, saddled horses at many Chicago tracks, dating back to the 1940s.
Volponi's win was the biggest upset in the Classic since Arcangues shipped in from France to California to win the 1993 running at odds of 133-1.
Volponi paid $89, $26.80 and $12.40; Medaglia d'Oro $4.60 and $3.60; Milwaukee Brew $9.60. The $2 exacta returned $463.60.
The race had been billed as a battle of 3-year-olds like War Emblem, Medaglia d'Oro and Came Home against older horses like Volponi and Milwaukee Brew.
"I didn't like the 3-year-olds in here at all," Johnson said, noting that many of them had not raced for many weeks.