Today on FOX Sports Arizona: Diamondbacks vs. Padres, 5 p.m.

—GameTrax: Stats and more

STATS Writer

The San Diego Padres’ woes at the plate and at Chase Field could cost them first place in the NL West.

If they can’t end those struggles Saturday night, the Padres may lose sole possession of the division lead for the first time since mid-June as they meet the last-place Arizona Diamondbacks.

With a 3-5 record since July 29, San Diego has seen its lead in the West dwindle to one game over San Francisco. The Padres (63-47) have been alone in first place every day since being tied with Los Angeles on June 17.

They produced just three hits in their latest defeat, 2-1 on Friday night in the opener of this three-game set. San Diego has hit .207 over its last eight games.

Miguel Tejada went 0 for 4 on Friday as his average dropped to .188 since being acquired from Baltimore on July 29. Adrian Gonzalez is mired in a 2-for-20 slump and has failed to drive in a run in six straight games.

Though Arizona (42-68) has an NL-high 31 home losses, San Diego is 1-3 at Chase Field this season and has lost 13 of its last 17 games there.

“These guys are a good team, and we know they’re going to manufacture runs,” Arizona interim manager Kirk Gibson told the Padres’ official website. “These are the type of games you are going to have to win (against) them.”

The Padres, who have won six of seven overall against the Diamondbacks, will try to turn things around against Rodrigo Lopez (5-10, 4.64 ERA), who is 1-4 with a 5.30 ERA in his last six starts.

The right-hander is 0-2 with a 4.80 ERA in two career starts against Padres, including an 8-5 loss July 17.

His counterpart in that game, Clayton Richard (9-5, 3.60), will start again Saturday searching for his third straight win and sixth in nine starts. The left-hander allowed a season-high 10 hits and four runs in 5 1-3 innings Monday, but he benefited from a rare offensive outburst from his teammates in a 10-5 victory over the Los Angeles Dodgers

The Padres, though, have since hit .139 and scored seven runs in four games. Will Venable provided his team’s only run Friday with his second homer in four contests.

San Diego homered four times in Richard’s only matchup against Arizona on July 17, and the left-hander earned the victory despite allowing five runs and nine hits over 6 1-3 innings.

Lopez has given up a major league-worst 27 home runs this season, including two in Monday’s 3-1 home loss to Washington.

“It’s not something I’m proud of,” Lopez told the team’s official website. “It’s ridiculous this year.”

He’ll try to help the Diamondbacks post their sixth victory in nine tries.

They likely will have to play without slugger Mark Reynolds, expected to undergo more neurological tests Saturday after being hit in the head by a pitch Tuesday night.

Adam LaRoche, who had a solo homer among his two hits Friday, has tried to pick up the slack by going 13 for 27 with four home runs in six games this month.

Arizona is batting .290 since July 29 — 36 points above its season average.

Updated Aug. 7, 2010