OAKLAND, Calif. -- Trevor May's major-league career will begin against the major league's best hitting team.

May, one of the Twins' top five pitching prospects, has been chosen to start Saturday's game against the Oakland A's, a team spokesman announced Friday. It will be the major-league debut for the 24-year-old righthander, who was acquired two winters ago from Philadelphia.

May has posted a 2.93 ERA in 17 starts at Class AAA Rochester this season, and three months ago had four consecutive starts without allowing an earned run. He missed three weeks in June and July with a sore calf muscle, but has a 2.41 ERA since returning from the injury.

The Twins, who have lost two straight games, will make a corresponding roster move after Friday night's game with the A's -- whose 557 runs scored are the most in the major leagues -- to make room for May. The roster spot doesn't necessarily have to come from the pitching staff, since the Twins currently have 12 pitchers, and have carried 13 most of the season.

May's debut on the West Coast will at least be relatively convenient for his family; May is a native of Kelso, Wash., about 50 miles north of Portland, Ore.

The Twins' rotation figures to undergo another change next week, when righthander Ricky Nolasco, scheduled to make his second rehab start for Class A Cedar Rapids on Sunday, returns to the team. In addition, recent acquisition Tommy Milone, a lefthander, is at Rochester and could move up. The current starting rotation includes Kyle Gibson, Kevin Correia, Phil Hughes and Yohan Pino, all righthanders.

May represented the Twins in the Arizona Fall League last October, posting a 3.21 ERA in nine outings, mostly in relief. His rise hasn't always been a smooth one; he spent two seasons in Class AA with the Phillies and Twins, posting ERAs above 4.50 each time. But May, who was acquired along with since-departed starter Vance Worley in a trade for former first-round pick Ben Revere, has been excellent from the start this season, his first in Class AAA, and until last Monday's start at Louisville, had not allowed four runs in any game in nearly three months.