CHICAGO – Grady Sizemore set the tone for the Cleveland Indians with his first swing.

Sizemore homered off Jose Contreras on the game’s second pitch, and the Indians added four more runs in the first inning on their way to a 12-5 victory over the Chicago White Sox in the season opener yesterday.

“You’re definitely excited,” Sizemore said. “I was a little jacked up up there. The crowd was getting into it.”

Then, he unloaded. And his teammates followed his lead.

The 12 runs were the most for the Indians on opening day since 1925, when they scored 21 against St. Louis.

After winning just 78 games last season, Cleveland knocked out Contreras in the second inning and pounded out 13 hits overall.

Sizemore’s homer was the Indians’ first leading off an opener in 19 years. He went 2-for-4 with an RBI and three runs scored.

“That gave everybody else confidence,” said Travis Hafner, who had two hits and scored three times.

“Huge,” starter C.C. Sabathia said. “Second pitch of the year and he goes deep. Hopefully, that’ll be a tone-setter for our season.”

Trot Nixon had three hits and scored three runs in his Indians debut, while Victor Martinez and Jhonny Peralta each had two hits and three RBIs.

That was plenty for Sabathia (1-0), who pitched well enough after taking a line drive to the left forearm in his final spring start. He allowed three runs and eight hits, struck out two and walked one in six innings.

Newcomer Darin Erstad hit a two-run homer in the first inning for the White Sox. Paul Konerko added a solo shot in the third, but the game was out of reach by then.

“They’re a great offensive club,” Konerko said. “They’ve been like that for the last few years. The good news is it was only one loss. It felt like it should have counted for more.”

A year ago, the White Sox raised the 2005 championship banner before beating Cleveland in the opener in a game that was delayed nearly three hours by rain and stretched into the next day. This time, they fell flat.

Things were so bad that manager Ozzie Guillen started experiencing flashbacks of April 18, 1991, when he was a shortstop on the team that lost 16-0 to Detroit in the first game at the new Comiskey Park.

“Thank God this only counts as one game,” he said. “I was sitting on the bench, and I was telling a couple of coaches it reminds me of when we opened this ballpark.”

Contreras (0-1) simply looked more like an old pitcher than his old self. He left with no outs in the second and the White Sox trailing 7-2 after allowing seven hits, walking one and striking out one. After missing the playoffs a year ago, the White Sox are counting on him to perform like the pitcher who started last season 9-0 – not the one who went 4-9 the rest of the way. But Contreras said through a translator there’s no reason to panic.

“I feel like we have a great team, great staff,” he said. “This is just the first game, and there is a lot more to come. You’ve got to get used to it because it’s going to be a tough race.”

Guillen said, “I know he will be better; he can’t be worse than that.”

Sizemore immediately served notice that Contreras was in for a rough outing, when he drove a 1-0 pitch to the bullpen in right for the eighth leadoff homer of his career.

Nixon and Hafner singled to right before Martinez drove in the second run with a single to shallow left. Hafner scored with two outs when Peralta singled on an 0-2 pitch.

Josh Barfield, the next batter, made it 5-0 when he knocked a two-run triple to right-center. The five runs were an Indians record for the first inning on opening day.

“It’s definitely a good way to get going,” said Sabathia, who’s 13-3 against the White Sox and 7-0 at U.S. Cellular Field. “I think it’s going to make everybody relax, to come out and have a good game like that, put up runs offensively, do the little things right. Hopefully, we can keep rolling.”

Notes: This was the third straight season opener and fourth in seven years between the White Sox and Indians. It was also the 26th time they opened against each other. … The Indians were 11-8 against the White Sox last season. … The 12 runs are tied for the second-most allowed by the White Sox on opening day.