ST. LOUIS (AP) _ Having achieved the lofty home run goal his 10-year-old son set for him this spring, Mark McGwire now tries to see if he can top it.

The St. Louis Cardinals slugger has six games left, all at home, to build on his major league record of 65 homers and try to hold off Sammy Sosa, who is two homers behind with five games to go, all on the road.

McGwire's stretch drive begins Tuesday night with the first of two games against the Houston Astros, and the team concludes its season with four against the Montreal Expos.

No. 65 was special for McGwire because that was the number Matthew McGwire, the Cardinals' batboy whenever he's in town, had forecast for his father before spring training.

``That's all I thought about when I was running around the bases,'' McGwire said Sunday. ``That ball means a lot to me. I hope I get it back.''

He could have had No. 66 on Sunday except for a controversial call by umpire Bob Davidson. The Cardinals asked the NL to review the ruling, but league president Len Coleman called St. Louis general manager Walt Jocketty on Monday to say the request had been turned down.

McGwire was given a double when Davidson ruled that a drive to left-center field at County Stadium was pulled in by a fan who reached over the wall.

``They said they were not going to look into it because it was a call involving judgment, not one involving an interpretation of the rules,'' Cardinals spokesman Brian Bartow said. ``They said the umpire's call would stand.''

How many more long balls does McGwire have in him? At this stage, no prediction is too outrageous.

``He's got a chance to do it every at-bat,'' Cardinals pitcher Kent Mercker said.

Or he could go the rest of the way without another homer and no one should complain.

``What Mark and Sammy have done this year, if they don't hit another one that's a lot of taters,'' second baseman Delino DeShields said. ``I've had my share, I'm satisfied. I don't know if he can push the envelope anymore.''

Likely, it will be someplace in between. Manager Tony La Russa figures the final count depends on the amount of pitches McGwire gets to hit. Give him one in the zone, and it's good-bye.

``He's going to be trying as hard as he can, and that's all you can ask,'' La Russa said.

As for McGwire, there are no predictions.

``I'm going to give it six great shots,'' McGwire said. ``Six games, and give it my best, and wherever the chips fall, they fall.''

The NL Central champion Astros have yielded five home runs to McGwire, although the starters on Tuesday and Wednesday, left-handers Mike Hampton and Randy Johnson, aren't among the victims.

He faced both pitchers on the Cardinals' first trip after he broke Roger Maris' 37-year-old record with No. 62. Three days after the historic homer and in the midst of an 18 at-bat homerless drought, he was 0-for-3 against Hampton. The following day, Johnson, though weakened by flu symptoms, held him hitless in two at-bats with a walk that broke Barry Bonds' NL record.

On the other hand, McGwire hit what then was the longest homer of his career, a 538-foot shot June 24, 1997, when he played for the Oakland Athletics and Johnson, a college buddy from Southern California, played for the Seattle Mariners. McGwire topped that shot with a 545-footer off Florida's Livan Hernandez at Busch Stadium on May 16.

For his career, he's 1-for-7 (.143) against Hampton with no homers. Against Johnson, he's 6-for-27 (.222) with two homers and 12 strikeouts.

Houston pitchers that are on McGwire's homer list are Jose Lima (No. 32), Shane Reynolds (No. 33), Billy Wagner (No. 38), Sean Bergman (No. 39) and Scott Elarton (No. 40). For the second straight series McGwire will miss Lima, among the league leaders in homers allowed with 32.

Houston pitcher will have a major say in who wins the home run derby because the Astros close the season with a three-game series against the Cubs.

McGwire has only one home run against the Expos. He hit his first career homer at Olympic Stadium, and ninth of the season, off Trey Moore on April 21. Moore has been on the disabled list since July after rotator cuff surgery.

The Expos' likely rotation for the final four games: Javier Vasquez, Miguel Batista, 14-game winner Dustin Hermanson and rookie Mike Thurman or Carl Pavano. Vasquez is among the league leaders with 30 homers allowed.

McGwire has little or no history against any of those pitchers, going 0-for-3 with three walks and a run batted in against Batista and 0-for-1 with a walk against Hermanson.

The Cardinals are 3-2 against the Expos, but the teams haven't played since April.