The tournament began with 6,240 participants with an entry fee of $10,000.

John Locher AP

LAS VEGAS -- The World Series of Poker main event returns Sunday offering a $7.6 million prize to the victor and it appears to be 24-year-old Joe McKeehen's to lose.

The Pennsylvania poker pro and mathematics graduate will have more than twice as many chips as his nearest competitor when the cards get dealt for no-limit Texas Hold 'em at the Rio All-Suites Las Vegas casino-hotel on Sunday.

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Its eight Davids vs. a self-described ''average Joe'' with a Goliath chip stack at the final table. Or if 61-year-old Neil Blumenfield gets his way, he has another tale in mind: going head-to-head with 72-year-old Pierre Neuville, ''and the young kid wins it all.''

Blumenfield, who once founded a tech startup, and Neuville, a former board game executive, are the oldest competitors in recent history to make it this far.

''It says a lot for the ability, my generation, to hang in there in a game that's become dominated by kids,'' Blumenfield said.

World Series of Poker tournaments began in May and continued for 51 days with 68 events, culminating with the annual main event. It's a grueling multi-day poker marathon that whittled down the competition from 6,420 entries at $10,000 each to nine players, all already guaranteed at least $1 million each.

Among the remaining ''November Nine'' are a poker star turned daily fantasy sports pro, an Israeli software developer and four young poker professionals from New York, New Jersey and Italy.

McKeehen has the largest lead a player has had since the World Series of Poker switched its format in 2008 to give people more chips. Chips have no monetary value in the tournament -- a player must lose all his or her chips to be eliminated or win all the chips in play to take the title.

Since 2008, only one other player has entered the main event as its chip leader and won the whole thing: Jonathan Duhamel in 2010.

''He's certainly not even-money to win,'' said popular poker celebrity Daniel Negreanu, who narrowly missed his own chance at the final table after being knocked out in 11th place by McKeehen in July. ''I expect him to make it down to the final three.''

The inclusion of Blumenfield and Neuville has changed the dynamic of the final table, too, he said.

''They don't play the typical style of poker,'' Negreanu said. ''They're more unpredictable. They'll add a little wrinkle.''

Casino owner Benny Binion started the series in 1970 as an invitation-only event. It was so casual the ultimate winner was chosen by the other, usually older, guys at the table.

Poker caught fire in 2003, when an accountant from Tennessee in need of no nickname -- Chris Moneymaker -- entered a $39 online poker satellite contest, won an entry to the main event and won the whole thing, inspiring other amateur players. Caesars Entertainment Corp. bought the tournament in 2004.

The number of poker tables in Las Vegas-area casinos ballooned from an average of 293 to 707 between 2003 and 2006. Online poker sites multiplied, too, until a U.S. law sent them packing overseas in 2006 and eventually a federal crackdown shut the sites down to American customers in 2011, with just a few states legalizing the sites since. The number of poker tables dropped every year starting in 2011 until there were about 603 in Las Vegas last year.

Poker pro Max Steinberg, for one, had replaced the card games with a new game for much of the last year: daily fantasy sports. Late to the poker boom but just on time predicting the rise of the fantasy sports contests, the Las Vegas resident won his entry into the World Series of Poker main event via a DraftKings fantasy basketball contest. Now he's back playing cards, singularly focused since Nevada regulators recently shut down unlicensed fantasy sports sites in the state since they consider it gambling.

For someone who needed to keep an eye on the poker prize in the days leading up to Sunday's main event start, the state's decision was, ''sort of a blessing in disguise for me.''