Angels left-hander Michael Roth will become the first pitcher drafted in 2012 to start a major-league game on Wednesday. (Getty Images).

Manager Mike Scioscia threw a bit of a curveball Tuesday night, naming Michael Roth his starter for the rubber match of the Angels’ series against Yu Darvish and the Texas Rangers on Wednesday.

Roth is a 23-year-old rookie who was in college a year ago. The left-hander has made four major-league appearances, all in relief, and only started 10 minor-league games at the end of last season. Nine came in the Rookie-level Pioneer League; the other came at Double-A Arkansas. Roth was drafted in the ninth round out of the University of South Carolina.

Williams is a 31-year-old veteran who’s started 92 major-league games. He and Garrett Richards were the presumed fill-in starters when the year began. Williams has pitched well in five relief appearances, allowing only four earned runs in 11 ⅓ innings.

Three of those innings came Sunday night in the Angels’ 13-inning win over the Detroit Tigers and that factored heavily into the decision.

“Jerome threw a lot of pitches two days ago, so I don’t know how much length there is there,” Scioscia said. “I think Michael Roth has a chance for more length tomorrow.”

Angel starters have had trouble pitching deep in games. Their starters have lasted longer, on average, than only three American League teams (roughly 5 ⅔ innings per start). Yet Scioscia tried his best to temper the expectations for Roth.

“It’s going to be a staff day,” the manager said. “If Michael Roth gets through six innings it doesn’t have to be. We can back him up with some guys if we have to. He’s a good candidate and it gives us more areas we can use Jerome if we need him.”

Roth would become the first player selected in the 2012 draft to start a major-league game. He’s already the second player from the class to reach the majors, behind Dodgers reliever Paco Rodriguez.

The Angels need a spot starter with Tommy Hanson on the bereavement list. Hanson is eligible to return in time for his next scheduled turn Monday, so Roth’s time in the rotation could be short-lived.