He has now entered territory traversed only by Maris and the legendary Babe Ruth, who hit 59 home runs in 1921 and 60 in 1927.
In two titanic games, the St. Louis first baseman has belted four homers - all of which traveled at least 450 feet - off the Florida Marlins' sorry and sorely inexperienced staff.
``They're a nice young staff,'' McGwire said, not long after two more young fans returned his historic home-run balls. ``They pitch aggressively and they go right at you. That's how you learn to pitch at this level.''
Now, after an off day today, he and the Cardinals will play five games with the Cincinnati Reds and Chicago Cubs in St. Louis, where McGwire will match-up with his principal rival, the Cubs' Sammy Sosa, who hit his 56th home run yesterday, an achievement eclipsed by McGwire's display.
``The fact that Sammy and I are hitting them on the same days is really just one of those coincidences,'' McGwire said.
McGwire victimized relievers Brian Edmondson and Ron Stanifer in the seventh and eighth innings of the Cardinals' 14-4 win.
The latest two massive shots, both to left field and the first into the upper deck, flew a combined distance of 955 feet, 33 feet farther than his 57th and 58th homers on Tuesday. They moved him past the trio who had hit 58 - Jimmie Foxx, Hank Greenberg and himself.
McGwire, who has 11 homers in his last 16 games, still has 23 games left to overtake Maris.
``It's not a question of if anymore to me,'' Florida outfielder Mark Kotsay said. ``As long as he doesn't get hurt, it's going to happen. He is just awesome to watch.''
McGwire refused to acknowledge that 62 homers were now a foregone conclusion, even if he had hit a homer in practically every seven at-bats during this remarkable season.
``If it's meant to be, it will happen,'' said McGwire, who raised his total for RBIs to 125 with four last night. ``I'll do my best to do it.''
From here on in, his best will have to come amid fevered circumstances like last night's, with national television cameras tracking him even as he took practice swings deep in a dugout tunnel; with 45,170 fans focusing almost exclusively on him, booing home-team pitchers who threw him balls; with flashbulbs gleaming like shooting stars on every pitch; with more than 400 media members in attendance; and with fans battling one another for the precious home-run balls.
Asked if he was experiencing the sort of anxiety that caused Maris' hair to fall out during his pursuit of Ruth in 1961, McGwire doffed his hat, pointed to his head, and said: ``I actually feel quite comfortable. I'm just going to enjoy it. I've been doing OK with it so far.''
In the meantime, as long as he remains in this frightening power groove, he can expect to see one intimidated pitcher after another staring back at him.
Florida's starter, Jesus Sanchez, turned his back to the plate in the first inning, squatted meditatively, scooped a handful of dirt, inhaled deeply, and, on this 87-degree night, blew into his hands as the Cardinals slugger entered the batter's box.
All that he and those other pitchers who will face McGwire and Sosa in their frantic rush toward Maris' record can hope to do is keep the ball in the park and their names out of the headlines.
Sanchez managed that before exiting in the third. Edmondson, another rookie, and the second-year Stanifer did not.
``That pitch he hit off me was only a couple of inches off the ground,'' Edmondson said. ``It's phenomenal. If he can do that with a pitch down there, I would hate to see what he can do with a golf ball. That would be scary to watch.
``All I can say is that there are 57 other guys whose names are on that list. I gave him a pitcher's pitch and the guy sent it into orbit. Give him all the credit. There realy wasn't anything I could have done differently. My personal opinion is that he is very relaxed right now.''
This latest barrage came after McGwire had electrified South Florida and the rest of America by tying and breaking Hack Wilson's National League homer record with two titanic centerfield bombs.
The first, a 497-foot bomb into the left-field upper deck, came off a low Edmondson 2-1 slider in the seventh.
``I figured he might throw me a slider there,'' said McGwire. ``And he did. But as it was coming in it kept getting lower and lower.''
Until he sent it higher and higher into the orange seats, above ex-Dolphin Jim Langer's retired No. 62. It was the third longest homer in Pro Player Stadium history, surpassed only by Andres Galarraga and, surprise, McGwire.
``I throw the pitch and I'm figuring, `Oops, I guess it's going to be 3-1.' And the next thing I know they've got two runs on the board. It's frustrating because when a guy is hot like that it puts you in a corner.''
Then, with two outs in the eighth, he crushed a fat Stanifer slider deep into the left-centerfield stands. It was his eighth multihomer game this season and the 51st of his career.
Edmondson was a nervous wreck when this series began. The Florida reliever not only feared McGwire, he idolized him, too. Growing up in Southern California, the 25-year-old righthander recalled being a fifth grader and going to watch McGwire play for USC.
``Personally, I've always been a big fan of his. I have an extensive collection of his baseball cards,'' he said. ``I've dreamed about the opportunity to face him.''
Now he's a footnote.
Chasing Roger Maris
The race to break the 61-home-run record
Yesterday: 2 for 3 Home runs: 59
2 homers Games left: 23
Yesterday: 2 for 4 Home runs: 56
1 homer Games left: 22