During the Kobe era at Lower Merion no moment was inconsequential, no drill unworthy of ultimate concentration. In one practice during his senior year, "just a random Tuesday," as coach Downer recalls, Bryant was engaged in a three-on-three drill in a game to 10. One of his teammates was Rob Schwartz, a 5' 7" junior benchwarmer. With the game tied at nine, Schwartz had an opening, drove to the basket and missed, allowing the other side to score and win. "Now, most kids go to the water fountain and move on," says Downer. Not Bryant. He chased Schwartz into the hallway and berated him. It didn't stop there, either. "Ever get the feeling someone is staring at you -- you don't have to look at them, but you know it?" says Schwartz. "I felt his eyes on me for the next 20 minutes. It was like, by losing that drill, I'd lost us the state championship."

This thing, this freakish compulsion, may be the hardest element of the game to quantify. There are no plus-minus stats to measure a player's ruthlessness, his desire to beat his opponent so badly he'll need therapy to recover. One thing's for sure: You can't teach it. If so, Eddy Curry would be All-NBA and Derrick Coleman would be getting ready for his induction ceremony in Springfield, Mass. But people know it when they see it. G.M.'s, coaches and scouts cite only a few others who have a similar drive -- Tim Duncan, Kevin Garnett, Manu Ginóbili, Steve Nash, Chris Paul and Deron Williams -- though they make clear that none of those stars are in Kobe's league. (In an SI poll earlier this season Bryant was a runaway winner as the opponent players feared most, at 35%.)

Even some of the great ones lacked it. Kareem Abdul-Jabbar says that when he was young, rather than challenging everyone as Kobe does, he "just wanted peace." "I think it's a quirk of personality," says Abdul-Jabbar. "Some of us are like Napoleon, and some are Walter Mitty."

Idan Ravin, a personal trainer who works with Paul, Carmelo Anthony, Gilbert Arenas and Elton Brand and is known by some in the league as "the hoops whisperer" for his effect on players, has even broken killer instinct down into components: love of the game, ambition, obsessive-compulsive behavior, arrogance/ confidence, selfishness and nonculpability/ guiltlessness. He sees them all in Bryant.