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STATS Writer

The uncanny consistency that has kept the San Diego Padres atop the NL West for much of the season may finally be fading.

The Padres face the prospect of their first three-game losing streak in nearly three months Sunday if they cannot defeat the Arizona Diamondbacks, who hope to become the second team to sweep San Diego this season.

The Los Angeles Dodgers swept the Padres (63-46) from May 14-16, the only time in 2010 that surprising San Diego has lost three in a row.

The Padres’ steady play is perhaps the primary reason they remain one game ahead of San Francisco in the division, but they’re looking more vulnerable than ever after losing four of five and six of nine.

Last-place Arizona (43-68) limited the Padres to three hits in a 2-1 win Friday, the third time on this road trip that San Diego has scored one run or fewer.

The Padres’ bats came alive Saturday, erasing a 5-0 deficit and tying the game on Adrian Gonzalez’s ninth-inning home run, but Chris Young’s second homer of the game gave the Diamondbacks a 6-5 victory.

“I loved the way we fought back,” manager Bud Black said. “We had our chances.”

Despite winning all six of its home games against the Diamondbacks this season, San Diego has lost four of five at Chase Field, where the Padres are 10-22 since the start of 2007.

They still like their chances of avoiding the sweep with Mat Latos (11-5, 2.47 ERA) on the mound.

The emerging 22-year-old has limited opponents to two or fewer runs in 14 of his last 15 starts while going 10-2 with a 1.66 ERA. But despite another fine outing Tuesday at Los Angeles, he was tagged with his first loss since June 4 in a 2-1 defeat.

“It was one of those tough-luck losses for him,” Gonzalez said. “He didn’t deserve to lose.”

Latos has yet to face the Diamondbacks, while his counterpart has faced the Padres once.

Joe Saunders (1-0, 1.69) shut down San Diego for 8 1-3 innings of a 9-1 win while with the Angels on June 13, 2009, and the left-hander has taken quickly to the NL since he was traded to Arizona last month.

In his home debut for the Diamondbacks, Saunders pitched a complete game in a 6-1 win over Washington on Tuesday.

“There’s a little bit of talk about the Diamondbacks gave up a lot and I’m here to prove the fans wrong, obviously, and prove my worth to the organization,” said Saunders, who was part of the trade that sent ace Dan Haren to Los Angeles.

Saunders hopes to bring Arizona a fourth consecutive victory, which would match its longest winning streak of the season. The current run has come entirely without slugger Mark Reynolds, who was struck on the helmet by a pitch Tuesday.

Reynolds, who leads the Diamondbacks with 25 homers, was available as a pinch hitter Saturday and may be nearing a return.

Updated August 8, 2010