VIENNA, SEPT. 24 -- Michael Chang destroyed the hopes of a nation today as he rallied to defeat Horst Skoff of Austria and carry the United States into its first Davis Cup finals since 1984.

After trailing by two sets to one when play was called because of darkness Sunday, Chang returned today to sweep aside the hard-hitting Austrian in the remaining two sets, 3-6, 6-7 (4-7), 6-4, 6-4, 6-3, withstanding leg cramps in the fifth set.

Andre Agassi had lost in straight sets Sunday to Thomas Muster, tying the best-of-five competition at 2.

Chang's victory puts the United States in the finals against Australia in St. Petersburg, Fla., Nov. 30-Dec. 2. Australia defeated Argentina over the weekend.

Dominant on Sunday with a strong cross-court forehand, Skoff had few opportunities today, silencing a raucous crowd of 17,000.

"It was a different Michael Chang and a different Horst Skoff out there today," said Tom Gorman, savoring his first chance to appear in the Davis Cup finals since he became captain of the U.S. team five years ago. "I feel terrific. I feel fabulous."

Chang, who said he telephoned his brother in California for advice before play resumed today, confused Skoff with an accurate kick serve to the backhand.

Resurrecting the tactic he used against Ivan Lendl to pull off a stunning, come-from-behind victory in the fourth round of the 1989 French Open, which he went on to win, Chang moved close to the service line to intimidate Skoff and jumped on second serves for several winners. He also directed a relentless attack against Skoff's weak backhand, drilling winners down the line when the Austrian attempted to run around the ball to hit forehands.

In the end, all four American team members played roles in the U.S. victory. Agassi beat Skoff on Friday. Doubles specialists Jim Pugh and Rick Leach beat Muster and Alex Antonitsch on Saturday.

Chang's triumph enhanced his reputation as a tough player to beat in matches that go five sets. The 18-year-old has won his last seven five-setters, including that match in the French against Lendl when he had to overcome cramps late in the match.

But one point before he finished off Skoff with a crisp cross-court service return for a winner, Chang's chronic leg cramps resurfaced, more from the tension than from the on-court temperature of 58 degrees.

Had the match continued, even for one more game, Chang said he is not sure he could have finished.

"It would have been difficult to go on because of the intensity of the crowd and the cold," he said. "I started to tighten up a lot. . . . If I had lost that game I don't know what would have happened."

Chang said the call to his brother, Carl, helped him devise an effective strategy. "He talked to me about when I was losing points, when I was getting in trouble," Chang said, "I applied it today and it worked well."

Asked to compare his victory here to the one against Lendl in Paris, Chang smiled. "Usually when you win a match that dramatic, usually the crowd roars. Here you win the match and everybody is quiet. I was a little awed."

Earlier in the day, normally reticent Viennese stopped Americans on the street to predict an Austrian triumph.

"You will see that Austria is not just a little point on the map," said travel agent Karl Horna, 27, in one such encounter. "It is a big tennis country."

Perhaps feeling the weight of these failed national ambitions, particularly after teammate and rival Muster had won both his singles matches, Skoff was subdued when he talked with reporters.

"Michael beat me in the most important match in my tennis life," he said. "I have lost not only for me. I've lost for Austria."