KANSAS CITY -- Twins outfielder Josh Willingham officially began his rehab assignment with Triple-A Rochester on Monday, and is expected to rejoin the Twins this weekend in Chicago against the White Sox.
Willingham, who had arthroscopic surgery on his knee on July 3, started at designated hitter for the Red Wings on Monday. He's expected to play five innings in left field on Tuesday and nine innings in left again on Thursday before being activated from the 15-day disabled list on Saturday.
"I think he'll probably DH, play the field, DH and then play the field," Twins assistant general manager Rob Antony said. "If all goes well through Thursday, he'll probably join us in Chicago on Friday and be activated on Saturday."
Willingham initially wanted to rejoin Minnesota in time for its doubleheader on Friday against the White Sox, but the Twins wanted him to play in four games before making his return. Willingham, 34, was hitting .224/.356/.398 with 10 homers and 37 RBIs before being placed on the DL on July 1.
"Hopefully those four games are enough to get his stroke back," Antony said. "He's been out a while, but he's a veteran guy and probably a little more prepared to handle this type of thing."
Outfielder Darin Mastroianni, who is on a rehab assignment with Class A Advanced Fort Myers, is expected to join Willingham with Rochester on Tuesday. Mastroianni, who had surgery on his left ankle on May 22, is also nearing a return with the Twins, but there's still no official target date.
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.