KANSAS CITY, MO. - Righthander Esmerling Vasquez joined the Twins after being called up from Class AAA Rochester on Saturday and is set to debut with the club Sunday when he starts against the Royals.

Vazquez, 28, has 141 games of major league experience with the Arizona Diamondbacks -- but all as a reliever. Sunday will mark his first major league start.

The Twins viewed him as a reliever as well, bringing him in as a nonroster invitee to spring training. In 23 games at Rochester, Vasquez was 5-4 with a 2.67 ERA. But then Rochester needed him to start late in the season, and he went 4-2 with a 2.93 ERA.

Now the Twins need him to start. "He's got a good, live fastball," manager Ron Gardenhire said. "It really jumps out of his hand. The breaking ball is OK, average. We haven't seen him as a starter, though.

"We were using him out of the bullpen. So he's stretched out and threw the ball great as a starter down there, so that's kind of exciting because we kind of viewed him as a reliever more than anything else -- a guy that comes in and lets it fly. Now we get to see what he's going to do here."

Vasquez will be the 12th pitcher to start for the Twins this season.

Start 'em all The Twins have seven pitchers who can start. Will they go with a six-man rotation the rest of the season?

They haven't named a starter for Wednesday's game in Chicago, and there are some indications that righthander P.J. Walters could be the choice. Walters, like Vazquez, was called up Saturday.

"This is the one opportunity where you could possibly go to a six-man or even seven-man [rotation] if you deemed it necessary," General Manager Terry Ryan said. "We're bringing up two starting pitchers, Vasquez and Walters, and we're certainly interested in how they responded."

Gardenhire said they will discuss this weekend what to do about the rotation. "I'll have to figure that one out as we go along," he said.

Sano gets honor Class A Beloit third baseman Miguel Sano, considered the top prospect in the Twins organization, was named the top prospect in the Midwest League in poll of managers. Sano, 19, is batting .260 with 27 home runs and 99 RBI in 127 games with the Snappers. He has committed 42 errors, but the vote is based on potential.

"They did not identify the errors," Ryan said. "There is no doubt that he is one of the best prospects in the game. We've got to get him to settle down on the defensive side of the ball. We think he can, because he's athletic enough and he's coachable enough. ...

"The thing we have to remember with him that this is really his first time playing third base for any length. He's always played shortstop."

Sano will head for Florida after the season and take part in the Twins' fall instructional league. Beloit has qualified for the Midwest League postseason.

Etc. Ryan said that there's still a chance for reliever Matt Capps, who is recovering from shoulder problems, to pitch for the club by the end of the season.