Defending champion Boris Becker faces challenges at every turn as a result of yesterday's draw for the U.S. Open, which starts Monday.

In the first round the second seed meets Juan Aguilera, who beat him this year in Hamburg. A potential second-round foe is former French Open champion Yannick Noah, while in the third round he could face Paul Haarhuis, who ousted John McEnroe last year. Possible fourth-round tests for Becker could come from Carl-Uwe Steeb or 15th-seeded Goran Ivanisevic, a rising star from Yugoslavia.

Top-seeded and top-ranked Stefan Edberg meets Alexander Volkov, but the spotlight in his section of the draw will be on Jimmy Connors and McEnroe. Connors, appearing in his 21st consecutive Open, opens against veteran Kevin Curren. McEnroe, a four-time champion whose form has slumped this year, has a tricky first-round match against Javier Sanchez.

Ivan Lendl, top seed the previous four years but third this year, opens against a qualifier and seems to lack strong competition until the quarterfinals, when he is seeded to meet Thomas Muster.

The top-seeded women avoided the most dangerous unranked opponents in the first round, with No. 1 Steffi Graf beginning her title defense against a qualifier to be determined. Her opponent in the round of 16 could be 14-year-old Jennifer Capriati, the 13th seed. Wimbledon champion Martina Navratilova, seeded second, takes on Federica Haumuller. Third-seeded Monica Seles, the French Open champion, drew Elena Pampoulova. . . .

Connors tested his heavily bandaged left wrist but not his game as he defeated mistake-prone Robert Seguso, 6-2, 4-6, 6-0, to move into the quarterfinals of the Tournament of Champions in New York. Connors next plays Lendl, top seed in this exhibition at the West Side Tennis Club.

In another second-round match, Henri Leconte defeated Sanchez, 6-2, 6-2, and Andrei Chesnokov led Christo van Rensburg, 6-2, 2-1 when rain halted play. The tournament lost Jay Berger with a badly blistered foot. That put Todd Martin, a Northwestern University student from Lansing, Mich., into the quarterfinals against Leconte.

Connors, who will turn 38 a week from Sunday, said he would decide Sunday whether to withdraw from the Open.