(My Sportsbook) - A showdown between two of the top pitchers in the National League is on tap for tonight at Chase Field, where Dan Haren will lead the Arizona Diamondbacks in the second test of a three-game series versus Jake Peavy and the San Diego Padres.

Haren is enjoying his first campaign with Arizona, having pitched to a 13-6 mark with a 2.96 earned run average in 25 starts. Haren has won five of his last six starts and defeated Colorado at Coors Field on Thursday, holding the Rockies to a pair of runs in eight innings of a 6-2 victory.

The right-hander, who is 9-3 with an ERA under three at home in 2008, is 2-1 in three starts versus the Padres this season. In six career games (5 starts) against San Diego, Haren owns a 2-1 mark and a 1.95 earned run average.

Haren will be opposed by Padres ace Peavy, last year's National League Cy Young Award winner. Peavy is having a subpar season in terms of wins but has been good enough in the Senior Circuit, as he is 9-8 with a 2.61 earned run average in 21 starts.

Peavy ended a personal two-game slide his last time out on Thursday versus the Brewers. He surrendered just one run and four hits in seven innings of a 3-2 victory, while recording eight strikeouts and three walks. Peavy has lasted at least six innings in each of his last 10 outings.

The righty is 1-1 versus Arizona this season and tossed seven scoreless innings of three-hit ball against the D'Backs on July 5 at Chase Field. Peavy is 11-10 with a 4.73 ERA in 24 career starts in this series.

Arizona hopes Haren can keep it atop the National League West standings in tonight's test. The club is one game ahead of the Los Angeles Dodgers in the West and has won six of its last eight games, including Tuesday's 7-6 victory in the opener of this series.

Newly-acquired outfielder Adam Dunn hit a two-run homer in his home debut and Conor Jackson added a pair of RBI in the win. Chris Snyder, Chris Burke and Mark Reynolds had an RBI apiece for the D'Backs, who took advantage of the Dodgers' loss to Colorado on Tuesday.

Diamondbacks starter Doug Davis earned the win and lasted six innings, surrendering two runs on seven hits while walking two and fanning six batters. Davis was winless over his previous three outings for Arizona, which opened a six-game homestand in winning fashion and improved to 34-26 as the host this season.

For San Diego, Adrian Gonzalez highlighted the offense by going 4-for-5 with two RBI and two runs scored. Chase Headley had two hits with an RBI and a run scored for San Diego, which has dropped five of its last seven games.

Josh Banks started for the Padres and suffered the loss, permitting six runs on four hits and a season-high seven walks with three strikeouts in four innings of work.

San Diego is 0-1 on a six-game road trip and 21-39 away from Petco Park this season.

The Padres officially dealt veteran starter and future Hall of Famer Greg Maddux to the rival Dodgers on Tuesday. The Dodgers will also receive cash considerations, while the Padres acquired two minor leaguers to be named later or cash considerations.