The top of the Brewers' lineup will have a decidedly different look tonight when they open a three-game series tonight at Pittsburgh.

It's a look general manager Doug Melvin hopes will go a long way in helping the Brewers catch and surpass the National League Central-leading St. Louis Cardinals.

Manager Ken Macha will install newly-acquired second baseman Felipe Lopez in the leadoff spot tonight, a day after Melvin sent a pair of minor leaguers to Arizona in exchange for the switch-hitter.

Lopez, 29, batted .301 in 85 games this season with Arizona. He hit six home runs, drove in 25 and stole six bases. He struck out 59 times (compared to 34 walks) but his .364 on-base percentage means he will be able to provide RBO-opportunities for sluggers Ryan Braun and Prince Fielder.

"He has been a very productive player at the top of the order with respect to both batting average and on-base percentage," Melvin said Sunday in a press release from the team.

He fills a pair of voids - atop the lineup and at second base - created when Rickie Weeks was lost for the season with a wrist injury. A career .963 fielder, Lopez has nine errors in 390 total chances this season.

Lopez will be a free agent in the off-season and has roughly $1.5 million remaining on his contract this year. He owns a career batting average of .266 with 77 homers, 359 RBI and 115 stolen bases. Milwaukee will be his fifth major league stop.

He will be the seventh leadoff hitter used by Macha this season.

Gamel sent down: To make room for Lopez on the roster, the Brewers optioned third baseman Mat Gamel back to Class AAA Nashville.

The rookie was called up to the majors on May 14 to provide an extra bat heading into interleague play. He remained with the team through the break as the offense, especially third baseman Bill Hall, slumped. But with Casey McGehee's emergence, Gamel saw his playing time diminish and he finished his Milwaukee stint with a .239 average, four homers and 16 RBI.

In Nashville, Gamel - considered one of the team's top prospects - will get the opportunity to play every day.

No rest for the weary: It didn't take long, but Macha is already concerned about his bullpen's second-half workload. The relievers were forced to cover 12.2 innings during the series in Cincinnati. None of the Milwaukee starters made it past the sixth inning during the four games. The Milwaukee bullpen is near the top of the National League with 292 innings of work.

Parra looks good: Manny Parra, in his second start since returning to the majors, looks like he's on the right track. He worked in and out of trouble Saturday night at Cincinnati, and though he threw 126 pitches over six innings, left the game with a 5-1 lead. In two starts since being demoted on June 13, he's 1-0 with a 0.69 ERA. Parra has stuck out 13 and walked just four. Prior to his demotion, he was 3-8 with a 7.52 ERA.

Injury report: Dave Bush underwent an MRI on his right arm last week after a rehab start at Class AA Huntsville went poorly. He was expected to return to the Brewers tonight, but it's no unsure when he'll be back with the club.

Quick hits: Sunday's 5-3 loss dropped the Brewers to 11-20 in day games (They're 36-25 at night). ... The three-game series at Pittsburgh wraps up a stretch that saw the Brewers play 14 of 17 games against NL Central opponents. ... Prince Fielder has 108 home runs since the start of the 2007 season; the second-most in baseball during that stretch. He needed just a triple Sunday for the cycle. ... Gallardo has just two victories in his last eight starts. ...Cameron has hit safely in five straight games and is hitting .388 in his last 15 games. ... Jody Gerut is 4-for-40 (.100) since coming to the Brewers in a trade for Tony Gwynn, Jr. ... Jason Kendall needs just 31 runs to get 1,000 for his career. ... Todd Coffey has allowed runs in just 10 of his 44 outings this season.

On the farm: To complete the Lopez deal, Melvin dealt outfielder Cole Gillespie and right-handed pitcher Roque Mercedes to the Diamondbacks. Mercedes went 1-1 with a 1.08 ERA in 29 games with Class A Brevard County this season wile Gillespie hit .242 with seven homers and 27 RBI with Class AAA Nashville.

This week: Milwaukee opens a three-game set against the Pirates at PNC Park tonight. After a day off Thursday, the Brewers are back home to open a seven-game homestand with three against the Atlanta Braves at Miller Park.

N.L. Central standings (through games Sunday):  1, St. Louis, 51-43; 2, Chicago, 47-43 (-2); 3, Milwaukee, 47-45 (-3); 4, Houston, 46-46 (-4); 5, Cincinnati, 44-47 (-5.5); 6, Pittsburgh, 40-51 (-9.5).