PHOENIX -- Brewers ace Ben Sheets is on his usual Spring Training quest. He's still searching for that elusive changeup.

It's a pitch that has mostly eluded Sheets throughout a big league career that began in 2001 and, despite injury frustrations in recent seasons, has included plenty of success. He has talked about it, tinkered with it, tried it in Cactus League games, but has yet to master baseball's ultimate "feel" pitch.

"They say it's repetition," Sheets said after surrendering his first runs of the year Tuesday. "Well, I've 'repetitioned' it."

Sheets tried a few changeups in an 8-4 loss to the Giants, and Brewers manager Ned Yost said the pitch is as good as he's ever seen from his likely Opening Day starter. But the consistency and confidence needed to make the pitch a staple of Sheets' fastball-curveball repertoire isn't there yet.

If it ever comes, Yost said, watch out.

"If he gets more confidence in that pitch it's like an extra bullet," Yost said. "Three pitches to get big league hitters out instead of two? It's never been as good as it is this year, and he's never worked on it as much as this year to gain confidence in it.

"That's how you get to the next level as a big league pitcher. You develop your pitches, then you refine your command on it. A big league starter that has 2 1/2 or three power pitches is going to be a big winner."

Even if the changeup rarely gets used.

"The more you throw it [the better], even if it only gets me a couple of outs a year," Sheets said. "That's fine. It might get me a big out in a game, a big double play against a big hitter. It might give me a big weapon."

He has tried out grips used by other changeup specialists, including former Brewers reliever Matt Wise. With Wise gone to the Mets, Milwaukee's best changeup probably belongs to Carlos Villanueva. New closer Eric Gagne has thrown the pitch in the past with tremendous success.

"I've talked to everybody, tried the way they hold it," Sheets said. "I can't hold it like that and throw it. So I stick to the one I've got and throw it when I can."

Where did he learn his changeup?

"I probably dreamed it up, to tell you the truth," Sheets cracked. "I really don't know. ... I've never been one to pick up a pitch and be able to throw it. I've thrown the same pitches all my life."

Sheets held San Francisco scoreless in the first inning and retired the first hitter he faced in the second before Giants catcher Eliezer Alfonzo sparked the rally with a single. Sheets got help two batters later when Brewers center fielder Mike Cameron threw out Alfonzo at the plate, but Dave Roberts followed with an RBI single and Fred Lewis and Aaron Rowand drove in two runs apiece before Sheets escaped the inning.

He recovered in the third inning, retiring the Giants' Nos. 7-9 hitters in order with two strikeouts.

"I felt stronger today," Sheets said. "The results were by far the worst, but I had a big, long inning and still felt good at the end of the inning."

His curveball is there, so much so that Sheets is trying to avoid throwing it too much to National League hitters. Instead, he's working on locating his fastball, something he hadn't done at times in the second inning Tuesday.

"That's what happens when you fall behind to big league hitters," Sheets said.

But at least it's happening in Spring Training, which Sheets knows as well as anyone is not an indication of the season to come. He feels his worst spring was 2004, but that turned into his best regular season, when Sheets pitched 237 innings and ranked second in the National League with 264 strikeouts and third in the league with a 2.70 ERA.

Still, getting knocked around Tuesday was no walk in the park.

"It ain't no fun," Sheets said. "There's nothing fun about it."