 As he worked his way through the Brewers' farm system, Villanueva was called up to the Brewers from Double-A Huntsville on May 22, .He made his Major League debut against the Cincinnati Reds on May 23, 2006, pitching a scoreless inning.After being optioned back to the minors, Villanueva was recalled again, making his first career Major League start for the Brewers against the Cincinnati Reds.