Padres 7, Diamondbacks 6: Yonder Alonso had two hits, including a go-ahead two-run homer in the fifth, and host San Diego held on to win the opener of the three-game series.

Jedd Gyorko contributed three hits, Everth Cabrera had two hits and two RBIs and Jason Marquis (3-2) threw six innings, allowing three runs, four hits and walking five for the Padres. Huston Street allowed a three-run homer to Gerardo Parra with two outs in the ninth before getting Martin Prado to fly out for his seventh save.

Miguel Montero had two hits, including a solo homer in the second inning for Arizona, which has lost four straight. Diamondbacks left-hander Wade Miley (2-1) went five innings, allowing four runs and nine hits while failing to earn a victory for the fourth straight start.

After the Padres scored twice in the second inning to take a 2-1 lead, Marquis walked two more batters in the fourth and this time they came back to hurt him. Eric Chavez tied the score at 2 with a one-out RBI double and later came home on a groundout by Cliff Pennington as Arizona took a 3-2 lead.

Miley walked the leadoff batter for the second time in the fifth inning and two outs later Alonso homered to right for a 4-3 lead. The Padres added an insurance run in the seventh and two more in the eighth, the last coming home on an RBI double by Chase Headley.

GAME NOTEBOOK: Padres OF Carlos Quentin was scratched from the starting lineup because of a “balky” right knee, but pinch hit in the eighth and struck out. Jesus Guzman started in Quentin’s place and went 1-for-4 with a two runs scored. … Padres RHP Tyson Ross, who is close to returning from an injury to his non-throwing shoulder, allowed one run in one inning of a rehabilitation start Friday for Triple-A Tucson. … Arizona’s losing streak is the longest since it dropped six in a row last season, beginning with a three-game sweep by the Padres.