Arizona @ San Diego preview

Last Meeting ( Sep 16, 2011 ) Arizona 0, San Diego 2

THE STORY: Arizona tries to prevent the National League West race from getting any tighter when it plays the second of a three-game series at San Diego on Saturday night. The Diamondbacks appeared to have a stranglehold on the division lead, but they have dropped back-to-back contests while second-place San Francisco has won six in a row to climb back within six games. Tim Stauffer pitched 6 2/3 innings for the Padres in Friday's series opener.

TV: 8:35 p.m. ET, Fox Sports (Arizona), Channel 4, 47 Uniradio TV (San Diego)

PITCHING MATCHUP: Diamondbacks RH Josh Collmenter (9-9, 3.40 ERA) vs. Padres LH Wade LeBlanc (3-5, 5.43 ERA).

Collmenter had given up just eight runs in his last 38 1/3 innings before being pounded in Sunday’s loss to San Diego (4 IP, 7 H, 6 ER, 3 BB). He had been outstanding in two previous appearances against the Padres, striking out six and walking none over seven shutout innings. Collmenter has been extremely erratic all year, holding opponents scoreless in seven of his 22 starts but yielding five or more runs in seven others.

LeBlanc hasn't had much to offer since rejoining the San Diego rotation for good in late July, allowing at least four runs in each of his last four starts. Two of those outings came against Arizona, but he managed to earn a win in his last trip to the mound Sunday despite giving the Diamondbacks four runs in 5 2/3 innings. In seven career starts against Arizona, LeBlanc is 2-2 with a 5.86 ERA.

ABOUT THE PADRES (64-87): Pitching generally hasn't been a problem for San Diego, with right-handed starters Stauffer, Mat Latos and Aaron Harang all boasting ERAs of 3.85 or lower and closer Heath Bell (38 saves, 2.61) regarded as one of the game's best. The offense, however, has failed to produce on a consistent basis, ranking among baseball's bottom three in runs scored (557) and most other categories. The Padres have stolen 163 bases – easily the most in the major leagues – while being caught just 41 times.

ABOUT THE DIAMONDBACKS (87-64): Arizona had been one of the hottest teams in baseball prior to Friday's setback, winning 18 of its previous 22 games to take control of the NL West race. RF Justin Upton remains one of the leading candidates for National League MVP honors, leading the surprising Diamondbacks with a .294 batting average, 30 home runs and 86 RBIs. Arizona is 30-16 since July 29, when it trailed San Francisco by four games. The team's magic number for clinching the division crown remains at six.

FINAL PITCH: San Diego third baseman James Darnell left Friday's game in the top of the seventh inning with an apparent shoulder injury.