Four years of preparation can be undone in a flash tomorrow.
Former New Zealand seamer Sir Richard Hadlee said the pressure would ramp up in the playoffs.
"It comes back to seven hours of cricket. This is four years of planning and preparation to get to seven hours of cricket and if you're good enough, you'll get another seven hours [in the semifinal]. Good enough again, you get a final, another seven hours, and potentially you could be crowned world champions," Hadlee said.
"Get it wrong in the quarter-final; drop a catch, top order fails, the bowlers don't get it right, the fielding's not as good as it has been, those sort of things, and it can all be over in that seven-hour period."
Hadlee, who collected 158 one-day wickets at 21.56, as well as a New Zealand record 431 test scalps, said he was surprised at the lack of yorkers being bowled at the World Cup.
"I'm astounded because if you look at the last 10 overs of teams batting, particularly batting first, [there is] 110, 120, 130 runs being conceded," he said. "You look at the way bowlers are bowling and there just aren't the yorkers. I know that with yorkers if you don't get it right, they'll go out of the park, like anything else, but there's a tendency to bowl back of a length, to bowl the slow bouncer, other different changes of pace, to bowl full and wide as another way [to stop the runs].
"So these are tactics and decisions, the way the modern game is but ... If you get the yorker right, it's pretty difficult to hit that out of the park."
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