ROME, SEPT. 3 -- U.S. athletes, who got off to a disappointing start last weekend at the world track and field championships here, redeemed themselves somewhat today as Calvin Smith won the men's 200-meter dash with a stirring comeback and Greg Foster captured the men's 110-meter high hurdles.

But the elation was tempered slightly because another U.S. athlete, Butch Reynolds, at the end of a season in which he has competed in 71 meets, finished third in the 400 meters, an event he was favored to win.

What the Americans didn't win in today's five finals, the East Germans did. Silka Gladisch added the women's 200 to her earlier victory in the 100; Thomas Schoenlebe won the men's 400 in the biggest upset in five days of competition at Olympic Stadium and Sabina Busch won the women's 400-meter hurdles in meet-record time.

An upset was brewing in the decathlon as defending world champion and world record-holder Daley Thompson of Britain, competing in his first decathlon in more than a year, struggled along in third place after today's events, with 4,363 points. Torsten Voss of East Germany led with 4,556 points, with teammate Christian Schenk fourth with 4,339.

Rob Muzzio of George Mason University was 11th in the decathlon with 4,131 points.

One other U.S. athlete won a medal today, with 1984 Olympic silver medalist Florence Griffith earning a silver in the women's 200 meters.

Today's results doubled the number of U.S. gold medals to four. The United States now has won 11 medals, tying it with the Soviet Union. East Germany leads with 16 total medals.

"I'm not surprised by the results so far," said U.S. men's coach Mel Rosen. "It's been a long season and this is a tough meet for us coming as late as it does. I said at the beginning of this meet we would probably get six golds. I think we still might by the time the meet ends Sunday."

Smith, whose 100-meter world record was obliterated Sunday by Canada's Ben Johnson, kept saying he had no reaction to the loss of the record. But when the loss of his 200-meter title seemed imminent, he turned on the speed. He won over France's Gilles Queneherve in a three-way photo finish so close it took five minutes for the judges to decide the winner.

In sixth place 80 yards from the finish, Smith began his charge. Both he and Queneherve were timed in 20.16 seconds, .02 seconds slower than Smith's meet record. John Ridgeon of Great Britain was third at 20.18.

Floyd Heard of the United States finished sixth.

The most joyous U.S. victor today was clearly Foster, who burst through the tape in 110-meter high hurdles in 13.21 seconds and immediately punched the air and jumped with joy at having retained the world championship he previously won in Helsinki in 1983.

"I was elated because I promised to win this one for my mother who died in an auto crash two years ago," Foster said. "I get very emotional about my mother."

Foster, who has had an up-and-down season, edged Jon Ridgeon of Britain, who finished second in 13.29. Britain's Colin Jackson, formerly of Southern Methodist University, was third in 13.38.

"I just wanted to finish this race because there was a lot of pressure on me," said Foster, who said he had trouble eating and sleeping today because of nervousness. "Now I just want a good indoor season, go to the Olympic trials and hopefully on to {1988 Summer Olympics in} Seoul to win a gold medal there."

The big surprise of the day came in the men's 400-meter race won by Schoenlebe, a previously little-known East German.

The prerace favorite was Reynolds, the 1987 NCAA champion from Ohio State who came here having run seven of the year's top 10 times in the event. But he appeared tired here even before he came down with a serious bout of diarrhea and stomach cramps in the days before the race.

"The race went according to plan," Reynolds said later, "I got off pretty fast, but I just didn't have it in me to go on as strong as I usually do.

"Now I'm just looking forward to 1988 and instead of bringing home a bronze, I hope to be bringing home a gold {from Seoul}."

Schoenlebe was timed in 44.33 seconds, his best time of the year. Nigeria's Innocent Egbunike was second in 44.56 and Reynolds third in 44.80, far below the 44.10 that is the best time he has run in the event this year.

Gladisch, who set a meet record of 10.90 in winning the women's 100 on Sunday, was never in trouble in the 200 final.

She was eight meters in front coming out of the turn and crossed the finish line in 21.74. It was four-tenths of a second faster than the previous meet record and just .03 seconds off the world mark shared by East Germans Marita Koch and Heike Dreschler.

Two other U.S. women, Pam Marshall and Gwen Torrence, finished fourth and fifth, respectively.

Busch also obliterated a meet record, winning the 400-meter hurdles in 53.62. The old mark was 54.14, by Yekaterina Fesenko of the Soviet Union. Australia's Debbie Flintoff-King was second, East Germany's Cornelia Ulrich third.

The strong East German showing could be attributed in part to the fact that they came here well rested after a relatively light season. The American athletes arrived at these championships after a grueling season that left stars such as Mary Decker and women's world 100-meter record-holder Evelyn Ashford unable to compete.

Schoenlebe said he had only competed in about 10 to 15 meets all year; only two of them, he said, were out of his country. Reynolds, whose season began with the academic year last September, has run almost five times as many races in that span.

"That is one hell of a lot of races," Foster said tonight. "You can't help but get tired and stale with a season like that."

Schoenlebe said that for him, the world championships were the main goal of the season and that everything he did was aimed at enabling him to perform at his maximum capacity here.

"There is no question that the East Germans and Russians have come here fresher and hungrier than us," said Rosen. "Even so, I don't think we are doing that badly."

Friday the finals in the women's long jump, 100-meter hurdles and 10,000-meter run will be held. The men will compete in the discus and complete the decathlon. The meet ends Sunday.