Sammy Sosa takes a shot at history, Hideki Matsui makes his major league debut, and most fans get their first look at Great American Ball Park as baseball gets into full swing today.

Randy Johnson, Pedro Martinez and Greg Maddux will be on the mound and Barry Bonds will be in the batter’s box, highlighting 12 games.

The season started Sunday night where it ended last year, in Anaheim, with the World Series champion Angels playing host to the Texas Rangers. Game Seven winner John Lackey threw the first pitch, a ball low to Doug Glanville.

Along with all the usual trappings of opening day — bunting, banners and even a former president throwing out the first pitch — there’s a different mood at many ballparks. Baseball starts against the backdrop of war, with American troops in Iraq.

“I can’t explain how I feel,” New York Mets standout Mike Piazza said. “You do get drained. It’s kind of like after 9-11, you’re watching TV, and you’re thinking about our people over there.”

Tom Glavine, Jim Thome and Robert Fick will be among the All-Stars playing for the first time in new places, and managers Dusty Baker, Lou Piniella and Felipe Alou will debut in different dugouts.

Sosa showed up in style — in a black stretch limousine — at Shea Stadium for the Chicago Cubs’ practice Sunday.

Today, he’ll try to become the 18th player to hit 500 home runs when he steps in against Glavine and the New York Mets. Chances are he’ll be bundled up — the weather forecast calls for temperatures in the upper 30s.

At Camden Yards, Baltimore and Cleveland had their workouts Sunday called off because of snow. It has been a tough spring for the Orioles, who dealt with the death of pitching prospect Steve Bechler in spring training.

“You put it in its proper place and go on about what you’ve got to do. Then you revisit it when you want to,” Orioles manager Mike Hargrove said.

Matsui attracted plenty of attention before playing his first game since leaving Tokyo. The Blue Jays took out an advertisement in Sunday newspapers in Toronto urging fans — in English and Japanese — to come out and boo the New York Yankees’ new slugger.

“I thought it was tasteless, especially in the climate of what’s going on in the world today,” Yankees manager Joe Torre said. “I understand fun and games, but I thought it was just too much.”

The ad was taped up to a door in the Yankees’ clubhouse as they arrived to work out a day before the opener. Roger Clemens will tie the AL record with his 13th opening-day start, matching Walter Johnson and Jack Morris.

Matsui said he wasn’t offended by the ad. But he admitted he’d not gotten that treatment in Japan, where fans hardly ever boo.

“I don’t have anything special to say,” he said through an interpreter. “I’m a little happy that the fans are aware of my name.”

And here’s another name for fans to get used to — Great American Ball Park, the new stadium in Cincinnati.

Former President George Bush will make the ceremonial first pitch before the Reds play Pittsburgh.

“This will be my sixth opening day, and we’ve only won one,” said second baseman Aaron Boone, who hit the last homer at old Cinergy Field. “There’s always so much hype with opening day here in Cincinnati. It’s such a crazy day, such a fun day, but we always end up losing.”

Atlanta and its revamped roster play host to Montreal. Maddux will start for the Braves, who lost Glavine and Kevin Millwood from their rotation but added Mike Hampton, Russ Ortiz and Paul Byrd.

Johnson already was focused on his start for Arizona against Los Angeles at Bank One Ballpark.

“The great thing about Randy Johnson is whether it’s opening day or a ‘B’ game in Tucson against the White Sox Double-A team, you can be pretty sure he’s going to bring everything he’s got,” Diamondbacks manager Bob Brenly said.