ARLINGTON -- They are both big boys, the Big Puma for the Astros and The Hammer for the Rangers. One leads the Majors in home runs, the other in RBIs.

One is 6-foot-1, 220 pounds and one of the greatest switch-hitters in the history of the game, while the other is 6-foot-3, 235 pounds and only beginning to establish his legacy as potentially one of the very best players in the game.

They are two of the hottest hitters in the game, and they are facing off this weekend in the Lone Star Series. Josh Hamilton, with two home runs and five RBIs, helped the Rangers take Game 1 on Friday, but Lance Berkman still went 2-for-4 for the Astros and takes a 15-game hitting streak into Saturday's game.

Both are surrounded by great hitters. The Rangers have Michael Young and Milton Bradley hitting around Hamilton, while Berkman is surrounded by Miguel Tejada and Carlos Lee.

But there is no doubt that Hamilton and Berkman are currently the No. 1 weapons for two powerful offenses, a couple of torrid bats positioning themselves well for a trip to the All-Star Game in July.

"We knew Berkman was the hottest hitter in the Major Leagues, and we saw that [Friday] night," Rangers manager Ron Washington said. "We threw a couple of pitches on the ground, and he still got the head of the bat on them."

Those hits were just singles. Imagine how the Astros felt when Hamilton went 5-for-5 with a walk in six plate appearances on Friday night. He had a single in his first at-bat, followed by two monster home runs, an infield hit and then a triple. The walk in the sixth plate appearance kept him from going for the cycle.

Astros starter Shawn Chacon, who faced Hamilton in his first three at-bats, simply couldn't figure out a way to get Hamilton out.

"[Hamilton] hit everything," Chacon said. "[His] first base hit was a fastball away; the second one was a changeup down and away, which I thought was a decent pitch. [The] next one was a fastball, which I thought, again, was a decent pitch."

That didn't stop Hamilton.

"[It was] pretty impressive," Berkman said. "That guy is hitting some pitches I probably wouldn't even swing at, and if I did, I'd be out. He's hitting them off the second deck for three-run homers and stuff. Tremendous bat speed, great-looking athlete. We saw some of that last year when he was with Cincinnati."

Both of Hamilton's homers were monster shots. The first one cleared the Rangers bullpen in right-center, and the second hit off the front of the upper deck in right-center. That one was measured at 451 feet.

Berkman can hit them a long way, too. He had one measured 493 feet while finishing second in the 2004 Home Run Derby at the All-Star Game in Houston. He's had two off the railroad tracks high above left field at Minute Maid Park and one in the upper deck in right field so far this year.

"Lance is a guy who, if you make a mistake out over the plate, he's going to hit it hard," said Rangers pitcher Jason Jennings, who faced Berkman over in the National League while with the Rockies. "When he squares it up, he hits it as hard as anybody I've ever seen. He's not as strong as Hamilton, but he hits it as hard as anybody when he really squares one up."

Both Hamilton and Berkman are squaring it up pretty good right now. Berkman went into Saturday's game hitting .394 with 15 home runs and 43 RBIs. Those home runs, Berkman's 46 runs scored and his unreal .800 slugging percentage all led the Major Leagues.

"It's been a lot of fun watching [Berkman]," Astros outfielder Hunter Pence said. "He does things that are pretty amazing, really. Seems like every game, he's coming up with two or three hits, big hits, homers, and it's been going on for weeks."

Berkman is hitting .552 (32-for-58) with 20 runs scored, seven home runs and 20 RBIs during his hitting streak. He also had a recent stretch during which he reached base 35 times in 50 plate appearances.

Astros manager Cecil Cooper, who played on some great offensive teams with the Red Sox and the Brewers, said he has never seen a player so locked in as Berkman has been recently.

"[I've seen] nothing like this, with the power and all of that stuff," Cooper said. "He's just been incredible. He's been as good as it comes these last three weeks or so."

Cooper joked that Berkman had a "down" night on Friday, going 2-for-4 against the Rangers. But the two outs were both deep fly balls to left field, and there's no doubt where those balls would have landed in the much cozier Minute Maid Park in Houston.

"You know, if we're playing at home, he might have had two homers," Cooper said. "He's been swinging it well, and we'll keep riding him as much as we can. I don't expect it to stop."

Hamilton's overall numbers aren't quite up there with Berkman. For example, he has a more earthly .599 slugging percentage. There is one category in which he has been exceptional. With a .333 batting average with runners in scoring position, Hamilton led all Major Leaguers with 49 RBIs entering Saturday.

"I've just felt this way all year when guys are out there," Hamilton said. "Once you start getting RBIs, you start getting confidence, and now I feel when there is a guy at second or third, I can get the job done. The more I do it, the more successful I feel."

Juan Gonzalez was the same way when he was at the peak of his career during the late 1990s, a guy who simply lived for driving in runs and putting up impressive totals. He set a Rangers club record with 157 RBIs in 1998, including 50 in the first 43 games. Hamilton has 49 in 43 games, one off that pace. Young called Hamilton "right near the top" of the great offensive players who have filled the Rangers lineup over the past couple of decades.

"The great players in this league not only have talent, but they have longevity," Young said. "They play for a long time. The great thing about Josh is, not only does he have incredible talent, but he has a hunger to be a great player."

Hamilton may have the edge on Berkman in terms of strength and speed. Berkman is five years older and has had knee surgery. But Berkman is a four-time All-Star with five seasons of at least 100 RBIs. He is a proven commodity who has taken his team to a World Series.

"They are both great hitters," said former Reds manager Jerry Narron, who was Hamilton's big league manager and an opposing manager in the same division as Berkman. "Berkman just has much more experience. I think with Josh, he's still learning; he's still scratching the surface. I think with Berkman this year, when you've got Miguel Tejeda and Carlos Lee around you, that means a great deal. But there is no doubt Berkman is an outstanding hitter."

Both Berkman and Hamilton are, and the two sluggers are at center stage in the Lone Star Series at Rangers Ballpark in Arlington.