By MATT BEARDMORE
STATS Writer

There are about six weeks left in the regular season, but the NL West-leading San Diego Padres already may be looking ahead to the playoffs.

A visit from the division-worst Arizona Diamondbacks is unlikely to change that.

San Diego tries to extend its home winning streak over the Diamondbacks to eight Tuesday night when the clubs open a three-game series.

The Padres (74-49), one win shy of matching last season's total, begin a stretch of 16 of 19 at home following a 7-3 trip. San Diego avoided its first three-game slide since May with a 7-3 win over Milwaukee on Sunday behind home runs from Adrian Gonzalez and Chase Headley.

The Padres more than doubled their division lead over second-place San Francisco since their last game at Petco Park and are moving closer to their first NL West crown since 2006.

"You can start to smell it," said Headley, who hit .368 with two homers and 10 RBIs on the trip. "We've got a month and change left to go and we're in good position.

"I think everybody is worried about going out there and giving it their all each and every day," he added. "Every win kind of gets you one bit closer to where you want to be. I think that's the mentality that everybody has."

The Padres, winners of four straight and 12 of 15 at Petco Park, are 6-0 at home against the Diamondbacks (49-76) this season while averaging 7.0 runs and batting .306.

Clayton Richard (11-5, 3.69 ERA) will try to continue that home-field dominance as he looks to win his career-best fifth straight decision. The left-hander is 2-0 with a 2.13 ERA in his last two starts after posting a 6.69 ERA in his previous seven.

"(Pitching coach) Darren (Balsley) has been great making some small adjustments to help get me back to where I was cruising," Richard told the Padres' official website. "The last couple of starts, it's starting to show."

Richard, 1-0 with a 9.00 ERA in two starts versus Arizona this season, pitches opposite Rodrigo Lopez (5-11, 4.94) for the third time in six weeks.

Starting with an 8-5 loss in San Diego on July 17, when he was tagged for a career high-tying four homers, Lopez is 0-4 with a 6.53 ERA in his last seven starts.

The right-hander was in line for his first victory since July 8 on Wednesday, but Arizona's major league-worst bullpen (6.06 ERA) gave up eight runs in the final two innings of an 11-7 loss to Cincinnati.

"We scored enough runs today to get the win," Lopez told the Diamondbacks' official website after the defeat. "We'll just get ready for tomorrow, try to forget what happened tonight."

Gonzalez, one homer shy of tying Phil Nevin for second in Padres history with 156, is batting .395 with five homers as San Diego has won eight of 12 against Arizona this year. Gonzalez, who has homered in three of his last five games, is 3 for 9 with a home run versus Lopez, who has yielded an NL-high 30 homers.

The Diamondbacks are coming off a series win over Colorado even though Chris Young went hitless in 10 at-bats, but the center fielder is 4 for 6 with two homers against Richard. Young is 8 for 17 with three home runs in his last five games versus the Padres.

Arizona is batting .238 while posting the league's second-worst road record at 19-40. The Diamondbacks' last victory in San Diego was 4-2 on Sept. 15.

Updated August 23, 2010

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