Allen WebsterThe Red Sox clinched the No. 1 spot in the American League on Saturday night, and now they’re taking measures to get their veterans some extra rest ahead of the playoffs.

Rookie right-hander Allen Webster will get the start in the Red Sox’ regular-season finale on Sunday. John Lackey, who is 10-13 with a 3.52 ERA on the season, was originally scheduled to get the start, but he’ll get the day off instead.

Webster has bounced back and forth between Boston and Triple-A Pawtucket this year, going 1-2 with a 9.55 ERA in six starts for the Red Sox. The 23-year-old was one of the main pieces in last August’s blockbuster trade that sent Adrian Gonzalez, Carl Crawford, Josh Beckett and Nick Punto to the Los Angeles Dodgers.

While he struggled in the big leagues, Webster fared much better in the minors this season. He finished 2013 with an 8-4 record, 3.60 ERA and 116 strikeouts in 105 innings with the PawSox this season. His last appearance for the Red Sox this season came on Sept. 15, allowing one hit and one earned run in one inning of work in a 9-2 win against the Yankees.

Webster will square off against Orioles righty Charles Tillman, who enters Sunday with a 16-7 record and a 3.62 ERA on the season.