ST. PETERSBURG, FLA., DEC. 2 -- Andre Agassi didn't feel well today.

In his last match of the 1990 Davis Cup final round against Australia, a moot point because the U.S. team clinched the cup Saturday, he left the court complaining of a strained sternum muscle after splitting two sets, 6-4, 4-6, with Darren Cahill.

"He may have been injured," said Cahill. "If he wasn't injured, it's a disgrace. . . . He didn't look injured to me when he was hitting his ground strokes, and that's the biggest part of his game."

Australian team captain Neale Fraser was even more blunt: "All these excuses come up all the time. I hope they {the Americans} can learn that, when they win, they can win graciously without coming up with all these excuses."

Today's controversy was only the latest involving Agassi, whose various ailments and uncharitable comments about his opponents have caused nearly as much commotion as the real news: The United States today officially captured its first Davis Cup title in eight years, defeating Australia, three matches to two.

Australian Richard Fromberg defeated Californian Michael Chang, 7-5, 2-6, 6-3, in the fifth and final match at the Florida Suncoast Dome.

Agassi and Chang won Friday's singles matches and the United States clinched the best-of-five final when the doubles team of Rick Leach and Jim Pugh pulled out a four-set victory Saturday over Pat Cash and John Fitzgerald.

As a result of Agassi's default today, Tom Gorman, who should have been rejoicing at his first Davis Cup triumph in five years as U.S. captain, instead found himself defending the behavior of a player with whom he has openly feuded for much of the year.

"He just didn't feel like he could continue," Gorman said. "He could hit his ground strokes, but he couldn't serve."

Agassi was not available to comment.

His departure came amidst a smattering of boos and renewed questions about his commitment to the U.S. team. The fourth-ranked player in the world, Agassi announced a few days ago that he would compete in the $6 million Grand Slam Cup in Munich beginning Dec. 11, and he clearly did not want to risk a more serious injury by continuing to play today.

He had his stomach taped during the second set, but apparently continued to feel pain when he tried to serve. After defaulting, he spent 45 minutes at the Bayfront Medical Center, where doctors diagnosed a tear in the rectus muscle under the sternum.

Agassi was not present for the awards ceremony late this afternoon in which the U.S. team received the giant silver cup.

Whatever his motivations, Agassi's actions this week and the general turbulence around the U.S. team all year have reignited criticism that Americans do not adequately appreciate the prestigious, 90-year-old Davis Cup competition. The U.S. victory here was supposed to change all that, but so far it hasn't succeeded.

The Australian team, proud of its Davis Cup tradition, issued a subtle reminder that some top U.S. players -- they did not have to specify Agassi -- seem more concerned with making money and achieving top rankings than with bolstering national pride.

"It would have been easy for us to go out there and go through the motions" in singles matches today, Cahill said. "But that's not the way the Australians do things. If we go down, we go down fighting."

Said Fraser: "Some of our guys have injuries. We play in pain, but we keep it quiet. We tough it out."

The anger the Australians feel toward Agassi stems in part from his brash opinions about Australia's inferiority on the tennis court.

To make matters worse, after Agassi needed five sets to defeat Davis Cup novice Fromberg, he explained that he had been fatigued because of a virus early in the week.

Today, in the person of Cahill, the Aussies struck back.

"Andre Agassi the tennis player is great," he said. "But apart from tennis, anything that comes out of his mouth is of very little significance. . . . The stuff he carries on with is needless. You don't have to say things that a 2-year-old could say."

The Australian point of view is shared by some Americans who have tired of Agassi's chronic lack of conformity. The 20-year-old bad boy from Las Vegas, who still sports shoulder-length, two-tone hair and lava-hued tennis attire, was booed several times by the partisan U.S. crowd when he repeatedly used drop shots in his match against Fromberg.

"I don't know that Andre is that well-liked here," Cahill said. "Although the 10- and 12-year-olds like him a lot."

Chang tried to put the best light on his teammate's penchant for controversy. "Andre sometimes is just difficult to figure out," he said.