Fifty-six players, including three of the top six in the world, begin competing at noon today at the newly refurbished Rock Creek Tennis Center in the Sovran Bank/D.C. National Tennis Classic.

There is a new, fast surface. There are new, more plentiful seats. And when the second round begins Tuesday, there will be Ivan Lendl, Boris Becker and Jimmy Connors. (The top eight seeds in the tournament, led by Lendl, Becker and Connors, drew first-round byes.)

Lendl, the French Open champion and Wimbledon runner-up, beat Jimmy Arias (the seventh seed here), 6-3, 6-3, yesterday for the championship of the Head Classic at Stowe, Vt.

Becker, who was upset in the second round at Wimbledon by Peter Doohan, came back with an epic 4-6, 15-13, 8-10, 6-2, 6-2 victory over John McEnroe Friday night in a Davis Cup relegation-round match at Hartford, Conn. The 6-hour 40-minute match was the longest in U.S. Davis Cup history.

Connors, who will be 35 in September (thus making him eligible, at least in age, for Grand Champions tour events like the one being completed tonight at Rock Creek), is playing in his first tournament since Wimbledon. He advanced to the Wimbledon semifinals before losing to eventual champion Pat Cash.

The Big Three will be challenged by players such as fourth-seeded and 17th-ranked Brad Gilbert of Piedmont, Calif., ninth-seeded and 69th-ranked Dan Goldie of McLean and 304th-ranked Michael Robertson of South Africa, the last of seven players who yesterday won qualifier positions in the main draw.

Robertson, 24, a doubles quarterfinalist with Tomm Warneke (another of yesterday's qualifiers) last year in this event and the U.S. Open, defeated John Zahurak of Fallston, Md., 6-7 (7-5), 6-3, 7-6 (7-4). The match was played before a few hundred spectators on a stadium court left vacant because the Prudential-Bache Grand Masters tournament matches had been pushed back to last night to beat the heat.

"It was better than {Saturday}, but it was still pretty hot out there," said Zahurak, 22, a senior at the University of Maryland who was named Atlantic Coast Conference player of the year in 1986, but sat out this year so he could concentrate on his engineering studies.

"I was a little nervous at first," Zahurak said. "But I think he was, too."TODAY'S MATCHES Stadium Court Noon

Jimmy Brown, Largo, Fla., vs. Simon Youl, Australia; Andre Agassi (10), Las Vegas, vs. Patrick Kuhnen, West Germany; Vince Van Patten, Hollywood, vs. Richard Matuszweski, Hopewell Junction, N.Y. Grandstand Courts 1 p.m.

Peter Moraing, West Germany, vs. Kelly Jones, San Diego; Michael Kures, Willow Springs, Ill., vs. Christian Saceanu, West Germany; Al Parker vs. Barry Moir, South Africa; Michael Westphal, West Germany, vs. Peter Lundgren, Sweden; Chip Hooper, Sunnyvale, Calif., vs. Martin Laurendeau, Canada; David Wheaton vs. Johan Carlsson (15), Sweden. Court to be Announced 4 p.m.

Christo Steyn, South Africa, vs. Joey Rive, Palm Beach, Calif. Stadium Court After 7 p.m.

Dan Goldie (9), McLean, vs. Blaine Willenborg, Miami Shores, Fla. Grandstand Courts 7:30 p.m.

Peter Fleming (16), Glen Cove, N.Y., vs. John Ross, Gainesville, Fla.; Stephane Bonneau, Canada, vs. Tomm Warneke, Lakeland, Fla.; Thomas Hogstedt, Sweden, vs. Jonny Levine, Phoenix.