(My Sportsbook) - Brandon Webb has failed in his last two bids to become the National League's first 20-game winner since 2005. Arizona could think of no better time than now for him to post that milestone victory.

With their lead in the NL West now down to a half-game, the Diamondbacks continue a three-game series with the second-place Los Angeles Dodgers this afternoon at Chavez Ravine.

Webb has been less-than-stellar on the mound in his two previous attempts at 20 wins. After allowing six runs over 4 2/3 innings in a loss versus San Diego on August 26, the 2006 NL Cy Young Award winner was tagged for eight runs (6 earned) on eight hits in just 3 1/3 innings versus the Dodgers on Sunday. Webb walked a season-high tying five batters in that outing.

The 29-year-old righty is 19-6 with a 3.19 earned run average and would become baseball's second 20-game winner with a victory tonight. Cleveland's Cliff Lee reached that mark on Monday.

Webb, who has already set a career high in wins for a season, is 10-4 with a 2.94 ERA in 17 career starts against the Dodgers.

Los Angeles counters with an emerging pitcher in Chad Billingsley. A first- round pick in 2003, Billingsley is 13-10 with a 3.13 ERA in 28 starts and two relief outings this year.

He bested Arizona on Saturday, holding the club to a pair of runs on nine hits over seven innings. His 13th victory of the season established a new career- high, passing the 12 he posted in 2007 in 43 games, 20 of those starts.

The 24-year-old right-hander is 5-4 with a 3.74 ERA in 11 games (9 starts) lifetime versus the Diamondbacks, but his win on Sunday was hit first in four tests (1-3) against them this year.

The Dodgers pulled to within a half game of first-place Arizona with Friday's 7-0 victory. A win tonight would give Los Angeles sole possession of first place in the NL West for the first time since April 4.

Andre Ethier was the spark last night as he went 5-for-5 with a homer and a career-high five RBI, helping the Dodgers win their sixth straight game. Ethier has hit nine homers in his last 20 games.

Russell Martin doubled and scored three runs in the win, while Derek Lowe tossed eight shutout innings.

Dan Haren (14-8) was charged with six hits and five runs over four innings for Arizona. In his last two games, both versus LA, Haren has given up 16 hits and 10 runs in 10 innings.

The loss was Arizona's eighth in its last 11 games.

These division rivals have now split 16 games this year, with Los Angeles now holding a 4-3 edge at Dodgers Stadium.