The Padres forced extra innings by overcoming a four-run deficit in the ninth, but Arizona got to Heath Bell (4-3) in the 11th to maintain its one-game lead over Los Angeles in the National League West.
Jeff DaVanon doubled to open the 11th and was sacrificed to third. Orlando Hudson drew a two-out walk and Eric Byrnes then drove in the go-ahead run with an infield single. Tracy followed with his home run to center.
The 11th inning assault made a winner out of Jose Valverde (1-3), who gave up two runs in two innings of relief.
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