NEW YORK - Stephon Marbury made it official last night: One year of college basketball was enough to prepare him for the NBA.

After one season at Georgia Tech, the 19-year-old guard said he had signed with an agent and would make himself available for the NBA draft.

During a news conference at Junior's, a Brooklyn restaurant famed for its cheesecake, one of which was named for him, Marbury made the announcement surrounded by family, friends and his college coach, Bobby Cremins.

''I've always worked hard for this. I've always watched the NBA growing up. I always watched Michael Jordan and Magic Johnson and I said I could be playing on the court with them. Next year, I will be,'' Marbury said. ''Opportunity is knocking, and I have to take advantage of that.

Marbury left no doubt that he won't be coming back to Georgia Tech.

''I don't want to prolong it. I have signed with an agent,'' who he identified as Eric Fleischer.

''I am putting everything behind me and focusing only on the NBA.''

Marbury had said as far back as November that he would leave college if he was going to be among the top selections in the June draft. Even though there were no assurances he would be taken among the top five picks, the information Cremins was able to obtain indicated the 6-foot-2 star would go early enough.

Marbury was selected rookie of the year in the Atlantic Coast Conference after averaging 18.9 points and 4.5 assists for the Yellow Jackets, who returned to the NCAA tournament this season after a two-year absence. They reached the round of 16 before losing to Cincinnati.

''I fully support Stephon's decision,'' Cremins said. ''I told him even before the season that he could be an NBA player, but first, he would have to become a good college player, and he did that."