Chicago Cubs pitcher Kerry Wood will retire on Friday, a source familiar with the situation told ESPN Chicago.com's Bruce Levine.
Wood, 34, is 0-2 with a 8.64 ERA and has been battling health issues all season.
Wood is best-known for his 20-strikeout game during his rookie of the year campaign in 1998, earning him the nickname "Kid K."
He was a driving force behind four playoff teams -- 1998, 2003, 2007 and 2008. He won two games against the Atlanta Braves in the NLDS in 2003, pushing the Cubs into the NLCS.
Unable to stay healthy as a starter, Wood remade himself into an effective closer.
He saved 34 games for the Cubs in 2007 and priced himself out of the Cubs' plans.
He signed a two-year, $20.5 million contract with the Cleveland Indians. He spent 1½ seasons in Cleveland before being traded to the New York Yankees in 2010, and was part of their bullpen as they advanced to the ALCS.
Wood returned to the Cubs in 2011 at a bargain price, $1.5 million for one year.
He had maintained a residence in Chicago and is considered one of the most popular Cubs in recent history.
Wood's final season was a rough one.
He barely pitched five innings in Cactus League play because of what turned out to be shoulder discomfort.
He walked three batters on Opening Day and blew a save. Two days later, he took the loss by giving up three runs.
The low point came on May 8 when a frustrated Wood tossed his cap and glove into the stands as he was walking to the dugout after being pulled by Cubs manager Dale Sveum.
Wood walked two batters and gave up two runs in the eighth inning that allowed the Atlanta Braves to break a tie game and eventually go on to a victory.
The normally accommodating Wood cut his postgame interview short and walked away when a reporter asked him about the incident after the game.
Wood had to return home during the middle of the Cubs' first road trip in April, and he received a cortisone injection in the shoulder.
He eventually went on the disabled list.
Tuesday was just the second outing for Wood since coming off the DL and he has given up two runs in each of those appearances.
The two-time All-Star finished with an 86-75 record and 3.67 ERA. He also had 63 saves.