Ken Griffey Jr. is leaving home to get back in a pennant race.

The Chicago White Sox acquired Griffey from the Cincinnati Reds on Thursday, hoping the 38-year-old outfielder can help them hold onto their slim lead in the AL Central.

The Reds sent Griffey and cash to Chicago for reliever Nick Masset and Triple-A second baseman Danny Richar. The deal was announced a half-hour before the 4 p.m. EDT deadline to make trades without waivers.

Griffey, who hit his 600th home run this season, agreed to the trade earlier in the day. Because of the cash transaction involved, the deal did not become official until the commissioner's office approved it.

White Sox general manager Kenny Williams coveted Griffey for several years. Once one of baseball's premier players, Griffey has never reached the World Series and has not even been in the playoffs since 1997 with Seattle.

"One of the things that factored into this was a guy who has had a great career but has not won a championship and how motivated he's going to be to get on that stage," Williams said. "That is a factor and will always be a factor for me."

Now older, it's uncertain how much Griffey has left in his oft-injured body _ it's been a long while since he was voted to the All-Century team.

Griffey played right field the last two seasons, but will return to center when he joins the White Sox on Friday for the start of a series in Kansas City. Manager Ozzie Guillen and the White Sox led Minnesota by 1 1/2 games when the trade was made.

"When I talked to Junior, he was very honest," Williams said. "He said, 'Well, I've got to tell you, I don't know that you're going to see the guy from Seattle.' I said, 'We're not looking for that guy from Seattle. What we're looking for is for you to use your instincts.'"

Griffey takes over for Nick Swisher, who moves to first base in place of the slumping Paul Konerko. Swisher also will give up his No. 30 to Griffey, who wore it during his earliest years in Cincinnati.

"I just think there's a lot of added things he can bring," Swisher said. "I mean, I had posters of that guy on my wall growing up. So I think it's going to be an awesome thing for all of us."

Reds general manager Walt Jocketty was surprised when the White Sox approached him on Wednesday. Griffey also was caught off-guard.

"I think he was just a little bit surprised, maybe, but I think he thought about it and said he wanted to talk to his family about it," Jocketty said. "I think he agreed it's a very good opportunity for him, and the club obviously wanted him and pursued him and came after him. That's got to be a good feeling for him, I guess."

The trade ended a bittersweet stay with his hometown team _ a lot of injuries, a few benchmark homers, no playoff appearances.

Notably, his last hit with the Reds was a homer.

Griffey was on pace to break Hank Aaron's home run record when he came to Cincinnati in a trade with Seattle before the 2000 season. A series of severe injuries dropped him well off the pace. He finally hit No. 600 this season _ only the sixth player to reach the mark _ but struggled mightily at the plate.

That short, sweet swing has slowed down this year.

Griffey hit a three-run homer in a 9-5 win at Houston on Wednesday that left him with 15 home runs, 53 RBIs and a .245 batting average despite playing in one of baseball's most homer-friendly ballparks. His 608th homer left him one behind Sammy Sosa for fifth place on the career list.

Now, Griffey can catch up with Sosa on the south side of Chicago.

His speed and range have diminished since he was the game's best center fielder in the 1990s. Guillen said Griffey will play center and will be a designated hitter at times. Griffey batted third with the Reds, but will drop to sixth or seventh with Chicago.

"We're going to start there," Guillen said. "I don't know if we were going to move him up or down, but we'll start there."

The Reds agreed to pay some of the money left on Griffey's contract to get the deal done. He makes $12.5 million this season, and has an option for 2009 at a $16.5 million salary. If the White Sox don't want to pick up next year's option, Griffey will be owed a $4 million buyout.

The Reds were interested in dealing Griffey because of the size of his contract and their plummet after the All-Star break, which dropped them back to near the bottom of the NL Central, 13 1/2 games out of first place. The Reds haven't had a winning season since 2000.

The trade that united Griffey with the Reds in 2000 was hailed as a major breakthrough for the franchise, but turned out to be far less than expected. After the 2002 season, former general manager Jim Bowden tried to trade Griffey to San Diego for Phil Nevin, who used his no-trade clause to block the deal.

Bowden was trying to work out a deal with the Yankees in 2003 before Griffey got hurt. The White Sox also showed previous interest in Griffey, but Reds ownership was reluctant to trade its most prominent player as he closed in on 600 homers.

Masset, a righty, was 1-0 with a 4.63 ERA in 32 games for Chicago. Richar hit .262 with nine homers for Triple-A Charlotte.

AP Sports Writer Jon Krawczynski in Minneapolis and AP writer Terry Kinney in Cincinnati contributed to this report.

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