(My Sportsbook) - After squaring off for the National League pennant in 2007, the Colorado Rockies and Arizona Diamondbacks both took steps backward last season. Each is hoping for a return to prominence in their 2009 campaigns, which begin when the two NL West rivals start up a three-game series this afternoon at Chase Field.

The Diamondbacks nearly made a return trip to the postseason in 2008, but wound up being overtaken by the Los Angeles Dodgers for the division title. Arizona did finish with a winning mark at 82-80, which was two games behind the Dodgers for the NL West's top spot.

Once again, Brandon Webb was a big reason why Arizona remained in contention all year long. The ace right-hander, who will take the mound for the Diamondbacks today, led the NL with a career-high 22 wins and posted a strong 3.30 earned run average along with 183 strikeouts.

Webb, the 2006 NL Cy Young Award recipient, has won at least 16 games in each of the past three seasons and made 33 starts or more in five straight years.

The sinker specialist was especially tough at home a year ago, as Webb amassed a stellar 11-2 record with a 3.35 ERA and three complete games in 16 starts at Chase Field. The Rockies found him tough to beat as well, with the Kentucky native going 3-0 with a 3.07 ERA in four outings versus Colorado in 2008.

For his career, Webb owns an 11-7 record in 25 career starts against the Rockies and has pitched to a 3.75 ERA in those games.

Colorado counters with a quality sinker-ball thrower of its own in Aaron Cook. The veteran righty was the lone bright spot on a disappointing Rockies' pitching staff last season, winning a career-best 16 games and delivering a solid 3.96 ERA in 32 starts.

The 30-year-old went 1-1 with a 5.19 ERA in three matchups with Arizona last year and is 5-4 with a 5.14 ERA in 18 lifetime appearances (16 starts) versus today's opponent. Cook has struggled when pitching at Chase Field over his career, however, having produced a 6.17 ERA in nine previous games (8 starts) despite a 2-2 record over that span.

Cook has started once previously on Opening Day. That came against the Diamondbacks at Denver's Coors Field in 2007, and he earned a no-decision after surrendering five runs in six innings.

Webb started that game for the Diamondbacks and was also not involved in the final outcome. He will be getting his fourth straight Opening Day assignment today and is 1-0 with a 4.00 ERA over the three previous lid-lifters.

The Rockies won a franchise-best 90 games during their unexpected World Series run in 2007, but injuries and poor pitching led to a disappointing 74-88 record for Clint Hurdle's club last year. Colorado will have a slightly different look this season, after shipping All-Star left fielder Matt Holliday to Oakland over the winter and adding pitchers Jason Marquis, Huston Street and Alan Embree through trades or free agency.

Colorado will also have to make do without one of its top pitchers this season, as left-hander Jeff Francis will miss the entire year after undergoing shoulder surgery in February. The 28-year-old won 17 games for the Rockies in 2007.

The Diamondbacks dominated the season series between these divisional foes in 2008, winning 15 of the 18 matchups and eight of the nine games played in Arizona. The Rockies have lost six straight times at Chase Field.