Chicago ? A grand slam, a bunch of runs, some pitches so tight they could have left marks and a bench-clearing fracas.

Just another day in the old, heated rivalry between the St. Louis Cardinals and the Chicago Cubs.

“I don’t really know why it happens,” said Jim Edmonds, who homered twice Wednesday in the Cardinals’ 12-4 rout. “The media was making a big deal out of this rivalry, and it was April and May. Everybody keeps building it up, obviously something’s going to happen, whether it’s just exciting baseball or a little bit of words back and forth.”

This time, it was both. Edgar Renteria hit a grand slam, Edmonds drove in four runs, the Cardinals spoiled Mark Prior’s second outing of the year, and some bad feelings that had been buried during the offseason resurfaced when Matt Morris buzzed a pitch at Derrek Lee’s head.

Both benches cleared in the fifth inning, but no punches were thrown and no one was ejected.

“It’s an intense rivalry,” said Morris, who gave up four runs and eight hits in five innings.

When Prior came off the disabled list last year, he went 10-1 with a 1.52 earned-run average. It looked like more of the same in his first start last Friday as he retired his first 13 batters, allowed two hits and walked none in six scoreless innings against Pittsburgh.

But he wasn’t nearly as crisp Wednesday. He lasted 32/3 innings and matched his career high with five walks, though one was intentional.