-- The best fastball in the National League was an accident, the result of two football licks delivered by the same child in the fields of Tannersville down in the deep south of Virginia. Crack! The right arm of a young Billy Wagner split in the ensuing pileup.

This happened twice. Same child. Same arm. Same sport. And each time the bulky mound of plaster was lathered on the right arm, rendering it useless until the bones had mended. Who knew what a fortuitous occurrence this would turn out to be for the Philadelphia Phillies?

"I threw with my right hand but after I broke my arm I still wanted to throw so I started throwing with my left," he said Wednesday night after firing 17 fastballs -- some as fast as 98 mph -- and two sliders at the Nationals for his 28th save of the year.

Then he dropped this.

"You know I can still throw with my right, too," he said.

You can?

As hard?

Wagner, blessed with a left-handed fastball that has sent speed guns flickering at 101 mph, shook his head and gave a dry chuckle. "If I could do that I'd be a lot more interesting to talk to," he said.

Right now the left arm is the difference for the Phillies in the final sprint for the playoffs. Wednesday night, after Wagner's last fastball was turned into a Vinny Castilla grounder to third base, the Philadelphia players all raced to the mound having leaped into the lead for the National League wild card -- something unfathomable just weeks ago when it seemed the Phillies were almost ready to trade the best fastball in the league to build for the future.

But that was back when there was doubt. He hasn't blown a save since May 24, blowing his fastball past hitters his last 19 save opportunities. There's no doubt now.

"When Billy throws, the ball just explodes," Phillies reliever Ryan Madson said. "I want to know what that feels like, just once."

Madson is 6 feet 6 inches tall. Wagner is seven inches shorter. Somehow, it doesn't matter.

"He's a country boy, man," Madson said. "Those guys are strong."

Against the Nationals, the ball exploded out of Wagner's left hand, sending the radar numbers fluttering into the high nineties once again. But this time his dominance was not a given. Jose Guillen took one of the two sliders Wagner threw for a ball, then lined a fastball into left field for a single. Next came Preston Wilson and an at-bat that you have when the season gets short and the games get big.

Nine straight fastballs he threw to the Nationals' center fielder. And Wilson kept fouling them off. This is excruciating for a closer because closers don't normally have the patience to keep flinging fastballs at hitters who won't strike out. Wagner is no exception to the rule. He heaved a fastball he was certain was about to hit Wilson in a sensitive spot and Wilson fouled that pitch off too.

Finally, out of desperation, Wagner threw his second slider of the night and it curled down toward Wilson's ankles. After swinging at nine straight fastballs, Wilson was rendered helpless. His swing missed the ball by several inches.

Still it's the fastball they come to fear. Tony Blanco saw one coming toward his head and his eyes grew huge. A couple of fastballs later he struck out, too. Many of them do; 60 in 58 innings this year.

In a few months, the best fastball in the National League will belong to a free agent and it is not impossible to see 100 mph on the scoreboard at RFK Stadium in the future.

But for now Wagner is here and no one else in the race for the playoffs has something quite like this -- a golden arm that was a gift from a football-playing kid in a country town called Tannersville.