The former National League MVP, became the fifth player to reach 600 career homers. Only Hank Aaron (755), Barry Bonds (748), Babe Ruth (714) and Willie Mays (660) have more career home runs than Sosa.

"It was something that cannot be explained," Sosa said. "Getting my 600th against the Chicago Cubs, and my first team (was) the Texas Rangers. It's like everything clicked. My emotions, I don't know what they are."

Sosa's historical home run came off a 1-2 pitch from Jason Marquis with two outs in the fifth inning. The pitch sailed over the right-center field fence into the Texas bullpen for his 12th homer of the year. The Rangers went on to defeat the cubs 7-3.

"It was a cutter I left up in the zone," Marquis said. "I went away from my strength and he made me pay for it. Other than the fact that it cost us the game, it doesn't really matter."

Sosa played for the Cubs from 1992-2004, winning the '98 NL MVP award and making seven All-Star teams while hitting 545 homers with Chicago.

In 2005, the Cubs' traded Sosa to the Baltimore Orioles in exchange for Jerry Hairston, a 29-year-old second baseman/outfielder, and two minor league players. After a sub-par season with the Orioles, Sosa's contract was not renewed and he was out of baseball for the entire 2006 season.

''I came back because I love baseball. It is my life,'' Sosa said about returning to baseball. "A lot of people doubted that I could come back. They didn't think I could do it."

"Right now, I feel great. I feel healthy and I feel like I can compete and go out there and do the things that I can do."

Sosa signed a one-year, $500,000 deal with the Ranger in 2007 which so far is a steal for the former all-star.