LAS VEGAS — Decisions became more meaningful at the World Series of Poker today, but players were still willing to gamble and play aggressively.

More than half of the remaining field — over 200 players — had busted out of the tournament after about 5½ hours on Sunday, when 407 players started with an average of just under 479,000 in chips.

The quick pace prompted tournament officials to stop play after six hours, after players originally planned to play 10 hours.

Minimum bets increase in the tournament every two hours, and the fast pace meant that the players remaining in the tournament had deep chip stacks relative to the minimum bets required on each hand.

That means as the tournament progresses, players can be even pickier with hands they are willing to gamble with.

With everyone left already guaranteed at least $27,469 in the no-limit Texas Hold 'em tournament, players hoped to avoid missteps that could cost them thousands and a shot at the top prize of $8.55 million.

"If you make a bad decision now, it hurts a little more," said Antonio Esfandiari, who started the day with a slightly above average chip stack.

Esfandiari said that the scope of the tournament wouldn't change his game, even as each bust brought players closer to a bigger payday for their $10,000 buy-in.

Smart raises, correct calls and proper folds helped some players build massive chip stacks as they sought a spot at the tournament's final table.

Tournament officials were adjusting the tournament to avoid long sessions and with a goal of reaching the final nine by Wednesday night or early Thursday.

Near Esfandiari, tournament poker player Kevin O'Donnell of Scottsdale, Ariz., spent several minutes deciding what to do with his top pair of queens with an ace kicker, after facing an all-in bet from an opponent.

"Nothing makes sense," O'Donnell said while looking at the board showing a queen, two sevens and a deuce.

O'Donnell has won nearly $753,000 in nine world series cashes, including nearly $495,000 for his 21st-place finish at the main event in 2006.

"Either you've got the same hand as me or you've got quad sevens," he said. "If you had quad sevens you wouldn't be worried about what I had."

O'Donnell finally folded, and his opponent flashed two queens for a full house, queens over sevens.

"This is like a win for me," O'Donnell said.

Across the room, seven-time bracelet winner Phil Ivey lost about 1 million chips in the first two hours on Sunday, most in three big pots.

After losing to a pair of sixes with two jacks and a 10 on the board, Ivey folded another hand to the same player after the opponent made a full house of kings over fives.

A few hands later, an opponent holding pocket aces caught a third on the river and bet 300,000 chips into a pot of under 200,000. Ivey called, taking his stack to 220,000 chips after losing the pot.

Ivey, who has won two gold bracelets at this year's World Series of Poker, rebuilt his stack above 1.2 million chips over the next 3½ hours.