Matt Garza, initially slated to start for the Cubs, will be replaced by Chris Rusin. Garza is close to being traded to the Rangers in a deal that will include third baseman Mike Olt and pitcher C.J. Edwards, according to sources.
Garza has fashioned a 6-1 record and 3.17 ERA in 11 starts this season.
Tyler Skaggs is slated to take the hill for Arizona, the southpaw's first start since July 10. That day, he lasted only 4 1/3 innings, having yielded three runs on eight hits to the Dodgers. In his previous effort, Skaggs blanked the Rockies on three hits over eight frames.
Arizona topped San Francisco on Sunday to avoid a sweep and maintain a half-game lead over the Dodgers in the congested National League West. The Rockies sit 3 1/2 games behind the D-backs, with the Giants 5 1/2 games back.
Cubs: Little mistakes proving costly
For the Cubs, who sit 10 games below the .500 mark, it has been a matter of one key mistake that has proven to be too much to overcome. On Saturday, right-hander Carlos Villanueva walked the opposing pitcher on a full count with two outs and subsequently surrendered a two-run triple to Dexter Fowler. Sveum can pinpoint a similar tough break nearly every night.
"You can look back on something, whether it was a pitch selection or [Saturday] night, it was obviously we walked the pitcher on a breaking ball," Sveum said. "Changed that whole game around, snowballed right after. Everything was set up to get out of that inning and get the pitcher out, walked him and three runs come in and obviously the gates open from there.
"But you can say that about every night."
D-backs: Gibson not worried about Parra
Manager Kirk Gibson isn't overly concerned about outfielder Gerardo Parra, who went 0-for-3 with a walk Sunday and is mired in a 2-for-31 stretch that has lowered his batting average to .280 from .299.
"He's fine," Gibson said. "He got real run down at the end of the first half and got beat up in a couple of the plays he had. One against the Mets took a lot out of him. He's standing back [in the batter's box] better now."
Parra's average sat above the .300 mark for most of the first half. Since June 23, the 26-year-old has no home runs and only one RBI. He has logged 80 at-bats in that time.
• Cubs rookie Junior Lake singled Sunday and now has a hit in all three of his big league games. He is batting .417 with a .462 on-base percentage.