OAKLAND, Calif. -- When the season began, right-hander Daniel Mengden was pitching for Double-A Midland and hoping he might get called up to the Oakland A's in late September.
Little did he know he'd be on the fast track to the big leagues.
Mengden went 2-0 with a 0.78 ERA in four starts for Midland and then 3-1 with a 1.39 ERA in seven starts for Triple-A Nashville.
Mengden, who didn't play a game above Class A in his first two professional seasons, made his major league debut for the A's on June 11 and will make his third career start on Wednesday afternoon against the Milwaukee Brewers at Oakland Coliseum.
Mengden is 0-2 but has a 2.25 ERA and 12 strikeouts in 12 innings.
"I pitched really well in Midland and got promoted to Triple-A," Mengden said. "A couple of injuries over here and it gave me a chance to get up here. I've been so grateful to have a chance. Trying to run with it as much as I can."
Mengden is only 23, but he has an old-school handlebar mustache, reminiscent of A's Hall of Fame pitcher Rollie Fingers, and a throwback windup, which includes a double-pump over his head and a couple pauses.
"I don't think that's something you could emulate or try to copy, but it works for him and it's been fun to watch so far," A's reliever Sean Doolittle said of Mengden's delivery. "For him, it's all about getting into that rhythm and keeping that rhythm throughout his delivery.
"I think it might kind of overshadow his stuff because he has really good stuff. All people talk about is the mustache and the delivery, but sometimes you forget that a big part of the reason why he's had success so far is because he's really good."
The A's acquired Mengden and highly touted catching prospect Jacob Nottingham from Houston in exchange for left-hander Scott Kazmir on July 23. Mengden finished last season at Class A Stockton, going 4-2 with a 4.25 ERA in eight starts.
Some 10 months after that trade, Mengden took the mound at Great American Ball Park against the Cincinnati Reds. He held the Reds to two runs and six hits in 5 2/3 innings but got as much attention for his windup and mustache, both of which he has had since his days at Texas A&M, as he did for his pitching line.
"If they're talking about me, it's a good thing," Mengden said. "If they want to talk about the mustache -- some people don't like it. Some people think it's stupid. In a way, it's a tough look to root for."
Mengden will face Brewers rookie right-hander Junior Guerra, who is 31 and took a much longer and slower route to the major leagues.
Guerra was signed as an amateur free agent out of Venezuela in 2001. He made his major league debut last year with the White Sox, appearing in three games, then was claimed off waivers by Milwaukee on Oct. 7.
"He's kind of been around the block a few times," Brewers catcher Jonathan Lecroy said of Guerra. "He's definitely a rookie up here, but I guess in life he's kind of a veteran. He's been around and played in a lot of different countries and experienced a lot of things.
"He's a good guy to have in the clubhouse, great guy, fun to catch. He gets after it, competes really hard, gets after it. He's a guy you know you're going to get everything he has whenever he goes out there."
Guerra is 3-1 with a 3.81 ERA in nine starts this year for the Brewers.
"He's had a good opportunity to come up and prove himself," Lucroy said. "So far, he gives us a chance to win every time we go out to play. That's all you can ask of a guy."