© 2010 MLB Advanced Media, L.P. All rights reserved.

07/24/10 3:12 AM ET

Martin, Parra working on different lessons

J.D. Martin and Manny Parra will be looking to put their most recent starts behind them when they take the mound Saturday night at Miller Park.

While both are coming off outings they hope to soon forget, the two hurlers have their sights set in different directions: Parra on improving against left-handed hitters and using his pitches better, and Martin on following in the footsteps of teammate Livan Hernandez.

The right-handed Martin said Friday he learned a lot from watching Hernandez throw a complete game Thursday against the Reds. After giving up six runs on six hits and three walks in his past start, Martin hopes to mirror Hernandez's ability to get hitters out with precision and deception rather than overwhelming velocity.

"He doesn't overpower guys," Martin said. "He has location and gets guys out. That's what I take out of that. I look at Livo a lot because I don't throw very hard. It's something I can look at and follow."

Parra, meanwhile, was roughed up to the tune of 10 earned runs on 10 hits Sunday in Atlanta. Manager Ken Macha and pitching coach Rick Peterson both said after the game that they would like to see Parra use his splitter more often, as he used it to strike out All-Star Brian McCann in the fifth inning Sunday.

"I'm convinced that the split should be his finishing pitch," Macha said. "Left-handed hitters have been giving him problems."

Lefties are hitting .393 and slugging .663 on the season against Parra, while right-handed batters are hitting .297 and slugging .402. His struggles have been extremely evident as of late, as he owns a 10.69 ERA in July, compared to just a 4.18 mark in June.

"I know what I've got to do," Parra said, "and I'll continue to work toward it."

Nationals: Detwiler will start Sunday
Left-hander Ross Detwiler will replace Luis Atilano in the starting rotation, as Atilano was put on the disabled list Friday retroactive to Wednesday with bone chips in his right elbow. Detwiler will make his debut Sunday against Milwaukee but will most likely not pitch more than five innings. He threw seven shutout innings Wednesday for Double-A Harrisburg.

Brewers: Hart day-to-day with injured wrist
Corey Hart injured his right wrist attempting to track down a fly ball in the third inning of Friday night's 7-5 win, finished out the top half of the frame but was then forced to leave. Hart slid into the wall as he moved toward the right-field line while trying to snag Cristian Guzman's foul ball. The outfielder, a persistent subject of trade rumors this month, underwent X-rays and an MRI on his right wrist, which both came up negative. He is day-to-day.

Worth noting
Brewers slugger Prince Fielder needs just one RBI to reach 500 for his career. Fielder, who went 1-for-4 on Friday but drove in no runs, will become only the 12th player in franchise history to produce at least 500 runs. ... The Nationals are just 8-10 this month, but 14 of their 18 games in July have come against teams with winning records. ... Of Washington's 71 games since May 5, 43 have been decided by two runs or fewer, including Friday night's 7-5 loss to Milwaukee.

This story was not subject to the approval of Major League Baseball or its clubs.