McGwire, in an 0-for-29 rut, told the St. Louis Post-Dispatch in Friday's editions he doesn't expect to be back at full strength from a knee injury for at least a year.
When asked if that could lead to his retirement at the end of the season, Big Mac said: "Good question.
"You talk to people about it and they say, 'You're not done. You're not done.' ... I think I'm still realistic. You have to look yourself in the mirror. There will be a day when you have to say, 'I don't have it anymore."'
"I'm embarrassed," the 37-year-old first baseman said. But he also said he hoped the second half of the season wouldn't be the end of his career.
Two other baseball greats Baltimore's Cal Ripken and San Diego's Tony Gwynn have already announced that they will retire at the end of the year. If McGwire joined them, he'd presumably be the third big-leaguer to retire after 2001 who would also be a lock on the Hall of Fame in Cooperstown.
McGwire signed a two-year contract extension earlier this season that will pay him $30 million in 2002-03. But he told the paper Thursday, "I don't want to cheat the team."
"A lot of people don't give a damn," he added. "A lot of players don't have pride. A lot of players just play for the money and they don't care and they just go home. But I go home, and I can't sleep. I get paid a lot of money to do what I do and I'm not doing it."
McGwire captivated baseball in 1998 when he broke Roger Maris' single-season homer record by hitting 70. He followed that by hitting 65 the next season, raising speculation that he could threaten Hank Aaron's career record of 755.
But tendinitis in his right knee limited him to 32 homers in 89 games last season, and he has just seven so far this year for a total of 561.
McGwire had surgery on the knee Oct. 21 and rehabilitated it during the offseason. He was limited during spring training and spent six weeks on the disabled list early in the season.
He said Thursday he is seeing the baseball, but has developed some bad habits because of the injury to his knee. While the joint is pain-free, he is lacking the leg strength he once had, he said.
"I'm at a crossroads right now," he told the paper. "I'm not 24 years old, and I don't heal as quickly. My legs are strong, but they're not the strength that I know.
"I'm not going to be at full strength for a year. I really took for granted how much I use my legs. And I'm paying for it right now. I'm hitting lazy fly balls that I should be driving over the fence."
Cardinals manager Tony La Russa said McGwire is close to his normal self, but is pressing a little bit, (doing) all the things you're doing when you're not getting hits."
But McGwire said it's much more serious.
"I live in the present and what's happening today. And I know what's happening today is not good. So it still amazes me why people want my autograph," McGwire said. "You don't want my autograph. I'm no good."
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