Fielder homered in the sixth off Rob Wooten with Shin-Soo Choo aboard.
''The past two or three days he is starting to be more consistent with his swing, starting to feel better at the plate,'' Rangers manager Ron Washington said. ''You could even see the difference in BP. He's just spraying the ball around and using his hands well. I hope he continues.''
Scheppers, who has made 115 relief appearances in the majors but is in the mix for a rotation slot, gave up two runs in the first on three hits, including Ryan Braun's RBI double. Scheppers settled down after that, retiring 16 of the final 18 batters he faced, striking out six and without walking a batter.
''He did a great job,'' Washington said. ''(Carlos) Gomez ambushed him with a fastball (leading off the game). Then he got Braun into a pretty good count and just hung a breaking ball. After that he put up five zeroes, (throwing) in and out, up and down, changing speeds.''
Yovani Gallardo, who earned his fifth opening day assignment for the Brewers, gave up four runs - three unearned thanks to two errors by Mark Reynolds and another by Lyle Overbay. Gallardo allowed eight hits, and struck out four in 5 1-3 innings.
Braun, who missed the previous two games with an illness, is hitting .458 in 11 games.
The Brewers committed five errors, which led to six unearned runs.
Leonys Martin went 3 for 4 for the Rangers with a double, scored a run and drove in a run.
Brewers: Gallardo threw 96 pitches in 5 1-3 innings.
''I felt good,'' Gallardo said. ''I think I made some pitches when I needed to. In the fourth, I got a little too quick, got away from my mechanics, just really rushing through it. It was groundballs getting through and things like that.''
Rangers: Scheppers threw 75 pitches, 52 for strikes.
''He showed me some stamina,'' Washington said. ''He definitely was consistent with his fastball and did a good job with his other stuff, too.''
Brewers: Shortstop Jean Segura (sore right arm) was not in the lineup for the second straight day.
Rangers: Right-hander Yu Darvish (stiff neck) was scratched from a minor league start in which he was scheduled to 90-100 pitches. Darvish said he should be fine to start the March 31 opener. ... Shortstop Elvis Andrus (right forearm flexor tendinitis) will not play the field for another week after being evaluated Friday by team physician Keith Meister. The blueprint is to have Andrus on a throwing program for seven days before playing shortstop. Washington said Andrus will DH Saturday. ... Outfielder-first baseman Mitch Moreland (left oblique tightness) has not played since Monday. ... Choo (sore left elbow) has been limited do DH duties for seven games. He is throwing up to 150 feet.
OVERBAY SLIDES CONTINUES
Overbay is 0 for 24 since his last hit on March 4, dropping his average to .121, 4 for 33 with 14 strikeouts. Overbay went 0 for 3 with a strikeout and committed a fielding error in the loss to the Rangers.
FIRST-ROUND PICK CUT
The Brewers released right-hander Eric Arnett, their 2009 first-round pick who never advanced above Class A. Arnett had an 8-20 record with a 5.18 ERA in 96 minor league games. He was the 26th player selected in 2009, one pick after the Angels drafted Mike Trout.
RANGERS ROSTER MOVE
The Rangers optioned right-hander Roman Mendez to Double-A Frisco. Mendez had a 4.50 ERA in four relief appearances. He started last season 2-0 with a 1.82 ERA in 16 relief appearances with Frisco, but went on the disabled list May 30 with an elbow stress fracture that did not pitch again.