Extra bases

• Felix Doubront will make his third Minor League rehab start on Sunday with Double-A Tennessee, and he is expected to start one of the Cubs' games on Aug. 30 when they play a day-night doubleheader against the Cardinals.

Doubront, sidelined with a left calf strain, has given up six runs on 12 hits over 10 innings in two Minor League games with Triple-A Iowa.

• Left-hander Zac Rosscup was recalled from Iowa to take Jackson's spot on the Cubs' 25-man roster. Rosscup is making his fifth stint with the big league team. In seven games, he's given up five earned runs over six innings. With Iowa, the lefty was 2-0 with four saves and a 2.10 ERA.

• Infielder Josh Vitters, the Cubs' first-round Draft pick in 2007, was placed on Triple-A Iowa's disabled list Thursday. Vitters suffered a broken ring finger on his right hand while reaching for second base on an awkward slide Wednesday. He was batting .213 with 14 doubles, 11 home runs and 38 RBIs in 112 games with Iowa.

Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.