This story appears in ESPN The Magazine's Feb. 16 Gambling Issue. Subscribe today!

BRENDAN STEELE HAD a feeling things were going a little too well. It was the Tuesday before the 2013 Players Championship, and Steele and Keegan Bradley stood on the 12th green at TPC Sawgrass with a 2-up lead on Phil Mickelson and Rickie Fowler in a best-ball practice match. Bradley was staring down a 10-foot putt that would give them a three-hole advantage with six to play -- not an insurmountable lead, but close enough. As Bradley read the putt, Phil spoke up from behind.

"Let me tell you," Mickelson began. "This is the whole match."

His voice was even, almost thoughtful. An onlooker might have mistaken it for candor. But Steele and Bradley did their best to tune him out. They'd been playing in practice rounds against Mickelson for two years now, and they knew what was coming -- a piece of vicious psychological warfare cloaked in a veil of objective philosophy. Money was on the line, real money, and Mickelson wasn't about to go down quietly. He had the commitment of a method actor in these moments, and to engage him, even just a little, would be to let him inside your head.

"If you make this putt," Mickelson continued, in his earnest way, "then we're going to be 3 down, and it's going to be too much to come back from. You guys are going to be excited, and you're going to have all the momentum."

The 42-time PGA Tour winner indulged in a dramatic pause. Bradley was ready to putt, but that didn't matter. The rhythm of Phil's monologue had to be respected. Truth be told, Steele and Bradley were caught up in the act too, even if, like a film they'd seen a hundred times before, they could recite the best lines along with him.

They'd had plenty of time to learn. Since the 2011 Players, when they'd been invited to their first of many Tuesdays With Phil, they had practiced girding themselves as he cycled between sarcasm, open mockery and his dreaded faux sincerity. The point of the matches was, in a way, to simulate the anxiety they all felt on Sundays, and nobody could ratchet up the pressure like Phil. He was, in Steele's words, an evil genius.

"I get in these games," Bradley said before the 2012 Ryder Cup, "and I've got more nerves than I do in the tournament." And so as Bradley finished lining up his putt, it hardly escaped his attention that he and Steele had the chance for a rare blowout win. Deep down, he knew Mickelson was right. If Bradley made the putt, it could put the match away.

"But!" Mickelson stressed, louder now, letting the word ring out for emphasis. "If you miss this putt, you're going to be so devastated that you're going to give us a hole in the next couple. After that, one of us is going to hit it close, and we're going to take another hole. And you're going to be so worried about blowing the lead that we're going to win the match.

"So be careful," he concluded, with a show of paternal concern. "You don't want to quick-peel this one low side."

And so it was that Bradley hit ... a quick peel on the low side, watching as the ball ran past the hole. And then he and Steele gave away the 13th with two bogeys. And then, on 15, Fowler stiffed one for a tap-in birdie to square the match. And two holes later, on the famed island green, Mickelson and Fowler sealed the match -- and the cash.

Walking off Sawgrass that day, Steele and Bradley were seething. And if someone had stopped them to say that it was only Tuesday and the loss didn't really matter at all, that person would have been lucky to get away with only an angry glare.

Often opponents during practice round matches, Bradley (center) and Mickelson (right) have teamed up for a 4-1 record in the last two Ryder Cups. REUTERS/Phil Noble

MANY SPORTS HAVE unhappy histories with gambling. Golf is not one of those sports. The major leagues had the Black Sox scandal. The NBA had Tim Donaghy. To know NFL history is to suspect that many games in the 1940s and 1950s were fixed. But the PGA Tour not only embraces its gambling past but virtually grew out of it.

From the 1920s through the 1950s, pro golfers were often glorified clubhouse hustlers, eclipsing their purses and funding their travel with the money they pocketed on their days off. Gambling, in a way, bankrolled the nascent tour. Gene Sarazen, Ben Hogan, Byron Nelson, Sam Snead -- each lived and died by the bet. Lee Trevino built his game hustling on the hardpan courses of Texas. And the lineage continued through the likes of such famed money-match players as Arnold Palmer, Lanny Wadkins, Tom Weiskopf, Ben Crenshaw, Mark Calcavecchia and Paul Azinger. Even the young Tiger Woods, according to his father, hustled older boys at the local course, returning home with fistfuls of bills.

It's a legacy that lives on in many ways, none more so than the Tuesday practice match. These matches usually begin, as they long have, with a simple wager: two-on-two best ball (the best score winning that hole for the team), with occasional individual ("indie") games between the players on different teams.

From that basic bet, permutations abound. There are "automatic 1-downs," where new, additional matches are started each time a player loses a hole -- leaving open the possibility that a player could lose 18 concurrent matches in a single round if he lost every hole. There's shot-by-shot "hammer betting," which allows a player to double the stakes during any given hole; his opponent can hammer back at any time, doubling the stakes again. There are "presses," which are like automatic 1-downs but can only be initiated by the trailing player whenever he chooses. Then there are the classic skills hustles: Four players pile into a bunker and drop a pile of Benjamins on whoever gets closest to the pin; they each attempt 90-foot putts, and if anyone actually sinks it, he pockets $500 from each of the other three.

Fowler, who finished in the top five of every major in 2014, frequents Mickelson's money matches. AP Photo/Peter Morrison

To your average schmuck at home, these amounts are staggering -- less so to your average PGA Tour player. Even middling tour pros easily pocket $1 million a year in earnings and more than double that in endorsements and appearance fees. But practice rounds are plodding affairs -- some players chip and putt from every side of every green to prepare for the tournament -- and the money has a way of keeping things, well, interesting. In Weiskopf's time, during the 1960s and '70s, the most a player could lose, even on a bad day, was a few hundred dollars. That price rose by the 1980s and '90s, when Calcavecchia and Azinger joined the games, and inflation has since run amok. Today's players don't like to talk about the amount wagered, but sources close to the tour say that a typical round will start with a $1,000 bet on every match. Totals can mount with presses and other prop bets, and if everything goes wrong, a player could potentially lose upward of five figures in 18 holes.

"I've been more nervous on the last hole trying not to lose two or three hundred bucks to Phil or Dustin [Johnson] or whoever than I have been on the last hole standing over a putt for $20,000," Calcavecchia says. "The last thing you want to do is pull 200 bucks out of your pocket and pay the guy off right there on the 18th green."

But pay they must. As Weiskopf says, there are no IOUs in this game: "Fast pay makes fast friends."

Consider that when Calcavecchia won $50 from Palmer at a British Open practice round at Royal Troon in 1989, he asked the grumpy legend to sign the bill. Palmer relented, and Calcavecchia thought it was a great start to the week. He was right -- he went on to win the tournament for his first and only major championship.

The matches pay dividends in other ways too, being the only time players get to practice the best-ball format featured in team events. "One of the main focuses of it is for the Ryder Cup," Bradley said at Medinah. "Phil does this, he picks young guys ... to prepare them for a match here in the Ryder Cup, and without a doubt he thinks about this stuff ahead of time."

Mickelson and Bradley, for their part, have parlayed their practice-round chemistry into the kind of Ryder Cup success that's become rare for the Americans. Their 4-1 record in the past two events was the product of a long-term plan. Before the Ryder Cup in 2012, Phil approached Bradley and told him simply, "We're going to play in the Ryder Cup, and we're going to win." Which makes the scratching and clawing and needling for one another's money something of a play-hate playdate.

THE MONEY MATCHES, to be sure, are not for everyone. Patrick Reed -- at 24 already one of the best young winners on tour -- prefers not to subject himself to anybody else's pace when he studies a course. Jack Nicklaus, as a rule, did not play for cash -- although that changed a bit in 1975, at a British Open practice round at Carnoustie, when he and Weiskopf were joined on the second hole by an Irish golfer named John O'Leary and an Australian named Jack Newton. The new arrivals wanted to play best ball, and after Nicklaus declined, Newton began to work the crowd. "Can you imagine?" he asked the spectators. "They've won three Opens between them, and these superstars are afraid to play us?"

" I've been more nervous on the last hole trying not to lose two or three hundred bucks to Phil or Dustin [Johnson] or whoever than I have been on the last hole standing over a putt for $20,000. " -- Mark Calcavecchia

Weiskopf liked Newton and thought it was funny, but Nicklaus grew increasingly irritated by the antics. He pulled Weiskopf aside. "You play your butt off today," he hissed.

The match was on.

Starting on the third hole, playing best ball with automatic 1-downs for 20 British pounds each, Nicklaus and Weiskopf made five straight birdies. On the eighth, a par 3, Weiskopf hooked a shot into a vicious crosswind, and the ball seemed to land comfortably on the green past a pot bunker. It was late in the day, and the only spectators behind the green were two old Scottish men. When he arrived at the green, Weiskopf couldn't find his ball, so he approached the men and asked if it had run off the putting surface.

"No, laddie," one said, calm as could be. "It's in the hole."

Just then, Nicklaus shouted the same news but with more enthusiasm. Weiskopf looked at the two men, puzzled.

"You two saw the ball go in the hole, and there was no expression, no emotion, nothing?"

The other man took the pipe out of his mouth. "Aye," he said, "but this is only practice today."

Practice or not, Nicklaus and Weiskopf caught fire. By day's end, in 16 holes, they had combined to make 14 birdies, one eagle and the ace. Newton, who had so rankled Nicklaus earlier, went noticeably quiet somewhere on the back nine.

When money is on the line, Mickelson will stop at nothing to get inside his opponent's head. Illustration by John Ueland, Ross Kinnaird/Getty Images (Mickelson head); Debby Wong/USA TODAY Sports (Fowler Head)

WOODS, FOR ONE, had a far less positive experience early in his career when he found himself playing for money against Mickelson. As the Associated Press' Doug Ferguson wrote in 2011, Woods faced off against Mickelson only once in a practice-round match. It was at the 1998 Nissan Open, and Mickelson, who won big, put photocopies of Tiger's old $100 bills in Woods' locker along with a note reading, "Just wanted you to know Benji and his friends are very happy in their new home."

Mickelson, the larger-than-life patriarch of today's money games, is a gambler's gambler. He's won huge sums on the Super Bowl and the World Series in the past, and he was actually reprimanded by the PGA Tour in 2001 after winning $500 from Mike Weir in the players lounge at the NEC Invitational when he predicted that Jim Furyk would hole a bunker shot. (Mickelson declined to speak to us for this story.)

So while money matches, on the whole, are less common on tour today than ever before, it's Mickelson's manic energy that has kept the games afloat, and his exploits in them are as fabled in golf circles as his five major championships: like the time he predicted his ball would hit the flag on the famed par-3 12th at Augusta National a split second after he made contact. Or the time he holed a big money putt after Azinger taunted him with a cocky "Putt it, bitch!"

More than anything, Mickelson demands his marks match his reckless courage, and not everybody is keen to spend that kind of intensity on a Tuesday. In 2010, Nick Watney joined Mickelson and Dustin Johnson for a practice round at the British Open. There were only the three of them, so Phil proposed a simple stroke-play match, with the highest score paying the winner $1,000 and the middle man walking away scot-free. Watney, knowing the amount could easily increase with presses or novelty bets, told them he preferred to play for less. "They started calling me names that shouldn't be in print," he says. "So I gave in to peer pressure."

Watney lost -- it was his first time playing St. Andrews -- and Mickelson won. On the 18th green, Watney counted out $1,000 and handed it over with a word of congratulations. Mickelson grabbed the stack of cash, gave it a quick glance and handed it right back. "This is Britain," he told Watney. "I need pounds."

Watney stared at him, hoping it was a joke. It wasn't. He had no choice but to pay Mickelson $1,700 to satisfy the currency exchange. "They've asked me to play again," Watney says with a slight smile. "And now I just say 'f--- you' and walk away."