Then Cameron Young, a young rising star on the PGA Tour, and Buba Watson, a 43-year-old two-time Masters champion, took one hit from the lead.
When the game ended on Saturday night, Pereira, who is 27 and only playing in his second major golf championship, confidently, even bravely, regained first place in the rankings. After a third round of 69, he will enter the final round on Sunday with a three-stroke lead over Zalatoris and Matthew Fitzpatrick of England.
Pereira, after stumbling in the middle of the circle, jumped over the other contenders in the third round with consecutive birds on the 13th and 14th hole. Then, with the full 18 green stands applauding for him, he ended his day by dipping a 27-foot blunt bird to move to nine less for the tournament.
While Pereira, who is ranked 100th in the world, is not a well-known name in professional golf, he has three places in the top 20 of the PGA Tour this year and won three times in the Korn Ferry Tour, the best circuit of the minor league tour.
Zalatoris had an uneven start on Saturday, shooting with four over 39 on the top nine, but stabilized, curing some of its problems to shoot a rocky 73.
After drilling his first two holes, Fitzpatrick was five points short of the rest of his round to shoot 67.
Young, whose father is David Young, a longtime golf professional at the Sleepy Hollow Country Club in the suburbs of New York, made a late attack when he scored a 296-yard par 4 17th hole, passing a green and making a short shot. With four birds in his circle, Young shot 67 and was in fourth place with a total of 5 less.