PEORIA, Ariz. (AP) _ Ryan Radmanovich hit a game-ending grand slam as the San Diego Padres rallied from seven runs down to beat the San Francisco Giants 13-10 Wednesday.

Trailing 10-3, the Padres scored one run in the fifth and five in the sixth to draw within one.

Ernie Young was 3-for-4 with a home run and three RBIs for the Padres. Radmanovich was 2-for-2.

San Francisco's Edwards Guzman was 3-for-4 with a homer, two RBIs and three runs scored. Jeff Kent went 2-for-4 with two RBIs, and Carlos Mendoza was 2-for-3 with a run and an RBI.

Radmanovich, a non-roster invitee battling to become San Diego's fifth outfielder now that Ruben Rivera has been released, connected on a fastball from right-hander Felix Rodriguez with one out in the bottom of the ninth to cap the Padres' comeback.

Charlie Greene started the inning with a walk, Donaldo Mendez singled and Bubba Trammell was hit by a pitch, loading the bases. One out later, Radmanovich hit his game-winning shot.

San Francisco's opening-day starter Livan Hernandez allowed four runs, six hits and four walks in five innings.

Jay Witasick, a right-hander in competition to be San Diego's No. 5 starter, allowed five runs, seven hits and hit two batters in three innings.

Left-hander Kevin Walker allowed another five runs in 1 1-3 innings for the Padres.