Astros play under N.L. rules for first time in 2013

The Astros open up a brief 2-game series in Phoenix tonight against the Arizona Diamondbacks. It will be the first time the Astros have played by National League rules this season.

The Astros, winners of 11 of their last 15, send Jarred Cosart to the mound against Josh Collmenter and an Arizona club that has won five of its last six. Barring an April 18th-like first inning collapse, Cosart will be the first Astros pitcher to step into the batter’s box this season. Jarred has allowed three runs or less in his eight starts since that fateful day in Oakland.

Collmenter (4-2, 3.63 ERA) had a rough outing in Colorado on Wednesday, but the right-hander tossed a 3-hit shutout against the Reds two starts ago.

Paul Goldschmidt leads an Arizona offense that is currently without the services of slugger Mark Trumbo. In Trumbo’s absence, the D-backs have received a boost from recent call-ups Didi Gregorius and David Peralta. Gregorius is 5 for 12 with a pair of homers in three games since being recalled from AAA Reno. Peralta has 12 hits in 28 at-bats since making his big league debut a little over a week ago.

The Astros have also benefited from outstanding production from a couple of rookies. George Springer leads the team in homers (12) and RBIs (35) and Jon Singleton has two homers and six RBIs in his first six big league games.

First pitch of Game 1 is scheduled for 8:40 CDT. Game 2 is tomorrow at 2:40. Brad Peacock gets the start for the Astros Tuesday against veteran righty Bronson Arroyo. The two teams then travel to Houston for another 2-game series to be played on Wednesday and Thursday — under American League rules.

In a flurry of roster moves to prepare for the Astros, Arizona has reinstated reliever J.J. Putz from the disabled list and recalled fellow right-hander Will Harris from Reno. To make room, the D-Backs have designated Trevor Cahill for assignment and placed Eric Chavez on the D.L. with a sore left knee.