Evans and Biondi Turn In Golden Efforts : Swimming: The Americans win the 400- and 100-meter freestyles. U.S. athletes also win a diving competition and the women’s 400 freestyle relay.

PERTH, Australia —  Matt Biondi retained the gold medal in the 100-meter freestyle and Janet Evans finally got her first world title today as things brightened considerably for the United States in the World Swimming Championships.

Earlier, Kent Ferguson of Boca Raton, Fla., gave the United States a surprise gold medal in the men’s 3-meter springboard diving competition, and the U.S. women took the 400 freestyle relay with a time of three minutes, 43.26 seconds.

The haul of four gold medals was a relief for American swimmers, who had just one gold going into today.

Biondi and Evans had the air over the Superdrome pool filled with the “Star Spangled Banner” back-to-back at awards ceremonies, the first time that has happened in the first three days of a meet the Americans were supposed to dominate.

“It’s been a long few days,” said Evans, of Placentia, who led the 400 freestyle start to finish and won in 4:08.63 seconds to beat Hayley Lewis, the Australian teen-ager who defeated her in the 200 freestyle Tuesday.

Biondi held off Sweden’s Tommy Werner in 49.18 to keep the world title he won in Madrid four years ago.

“When I stood on the dais, I thought, ‘I’m the fastest swimmer in the 100 freestyle on the whole planet,’ ” Biondi said. He sang the national anthem on the medals stand, then presented his victory bouquet to a woman standing at poolside.

Both winning times were well off the world records Biondi and Evans hold, 48.42 for the men’s 100, 4:03.85 for the women’s 400. But neither champion seemed to mind. They were winners all the same.

“It doesn’t matter,” Evans said, “As my dad says, in 10 years 4:08 will mean nothing and I’ll still be a world champion.”

It was the first world title for Evans, who won three gold medals at the 1988 Olympics, including the 400 freestyle. The victory gave Evans revenge for Lewis’ win Tuesday in the 200 freestyle. It also helped take the sting out of a disappointing fourth in the 400 individual medley and a disqualification in the Evans-anchored 800 freestyle relay Monday.

Evans holds the world record in the 800 freestyle and goes for the championship in that event Saturday.

Ferguson turned in a sensational final dive to hold off China’s top-rated Tan Liangde and maintain U.S. mastery of the event in world championships.

“I am in a state of disbelief. Wow, wow, wow!” Ferguson said.

Ferguson is a top-flight diver with 14 career international victories before today, but never one as big as this.

Tan was runner-up to American Greg Louganis at both the 1986 world championships and 1988 Olympics. He beat Ferguson at last summer’s Goodwill Games and generally is acknowledged as the best men’s diver in the world.

The U.S. women took the 400 freestyle relay with a time of 3:43.26. Germany was second in 3:44.37, with the Netherlands third in 3:45.05.

The U.S. team was made up of Nicole Haislett of St. Petersburg, Fla.; Julie Cooper of St. Louis; Whitney Hedgepeth of Roanoke Rapids, N.C., and Jenny Thompson of Dover, N.H.

The victory was especially sweet for Haislett, the women’s 100 freestyle winner but the goat of the relay disqualification, when she swam the second leg but left the side of the pool too early.

Haislett swam first this time, trying to lower her American record of 55.17. Opening legs of relays are recognized for record purposes. She put the U.S. in the lead, but her split was 55.74.

Hungary added its third title, with Olympic silver medalist Krisztina Egerszegi taking the women’s 100 backstroke in 1:01.78 over teammate Tunde Szabo.

Martin Lopez Zubero, a University of Florida student, gave Spain its first gold medal in the men’s 200 backstroke in 1:59.52.