Soviet high-jumper Vladimir Yashchenko leaped higher than anyone in history Sunday. He came down with a thunderous thud yesterday.

It all fell apart, said U.S. sources at track competition in Milan, Italy, after a night of "truly wild celebration," a liaison with a woman member of the polish team, some old-fashioned hard drinking and a shouting match with Soviet team leader.

Yashchenko, 19, ended up "somewhat in disgrace," said the U.S. sources. The cruel upshot for the Americans was that the Russian was banned by his own countrymen from defending his new title against American leaper Franklin Jacobs.

The Americans, in Milan for today's unprecedented U.S. Europe indoor meet, blasted the Soviets for "trying to play a political game by having Yashchenko in (Sunday's all-European) . . . meet with no chance of his being upstaged by Jacobs."

But from all appearances the 6-foot-5 skybuster was in no shape to compete. He was locked in his room and even the Americans conceded he had to be nursing a killer hangover.

They said when Yashchenko got mixed up with the Polish woman Sunday might it irritated her male teammates. A scuffle ensued. The Soviet team leader interceded and rebuked his star athlete. Yashchenko reportedly returned the fire, shouting, "Get out of here; you are just a politician and you don't know anything about athletics."

Officially, Yashchenko is said to be out of the competition because he was worn out by the 20 jumps he made in climbing to the new record of 7 feet 8 1/2 inches. Yashchenko also holds the world outdoor record of 7-7 3/4, set last summer in a junior meet in Richmond.

Jacobs was crushed. He held the old indoor record of 7-7 1/4.

"We heard about it just before our plane took off and finding out that, he won't be competing is really a letdown," Jacobs said. "It just blew my mind when I heard what Yashchenko had done.

Apparently blew Yashchenko's too.