McEnroe All Class on Grass; U.S. Leads, 2-0 : Davis Cup: Aging American star beats Spain’s Carbonell after Gilbert defeats Sanchez.

With his 32-year-old left arm conducting tennis opera again on the kind of court he was born to play, John McEnroe was saying his goodbys and preparing to walk off into history.

He said a quick goodby to Spain’s Tomas Carbonell, who was badly overmatched on the grass courts of the International Tennis Hall of Fame and lost to McEnroe Friday in three immaculate serve-and-volley sets.

“I was trying to do my best,” said Carbonell, who was playing his first Davis Cup match. “But he was just too good.”

Afterward, McEnroe waved all but goodby to Spain’s chances in this Davis Cup quarterfinal round, which hinged almost totally on at least splitting Friday’s two singles matches. Before McEnroe’s 6-3, 6-2, 6-1 victory, Brad Gilbert had defeated Spain’s top player, Emilio Sanchez, 6-4, 6-4, 6-2.

The U.S. doubles team of Rick Leach and Jim Pugh can clinch the victory by defeating Spain’s team of Sanchez and Sergi Casal today. If they don’t, either Gilbert or McEnroe can do the honors Sunday, when Gilbert plays Carbonell and McEnroe meets Sanchez.

“I expect Leach and Pugh to win,” McEnroe said. “And if they don’t, there’s no reason Brad and I can’t go out and play some more.”

And most movingly, McEnroe gave a conditional, nostalgic, melancholy goodby to his long, successful run on the U.S. Davis Cup team.

With several younger Americans ranked higher than he ever will be again; with his talking about retiring in a year and a half, possibly sooner; and with the probability that the United States won’t play any more Davis Cup matches on grass this year, it is time, to McEnroe at least, to acknowledge that this may be the end.

“After this, I feel I can go out with my head held high,” McEnroe said of his Davis Cup career. “I was here. I’ve never played a Davis Cup at home on grass before, so it’s nice to have done it here at what might be the end.”

McEnroe, who has won more Davis Cup matches, 40, than any other American and, according to team captain Tom Gorman, will go down as the greatest Davis Cup player ever, says he will play for America any time he is asked.

But he may not be asked again.

If the United States moves on to play Germany in the semifinals, McEnroe says he understands that it would be best for Gorman to choose to play on a slower surface, where Andre Agassi or Jim Courier have better shots at upending German superstar Boris Becker.

“It’s disappointing, but I understand it,” McEnroe said. “I’m just sorry I missed out on some of the matches the past few years.”

McEnroe did not play Davis Cup from 1984 until 1987 for various reasons, including problems with Gorman.

If Friday’s match was the last meaningful performance by McEnroe in Davis Cup play--assuming a U.S. victory in the doubles, McEnroe’s match Sunday will be merely an exhibition--his play was suitable for the occasion.

After Carbonell, 70th in the world, put up a surprisingly tough fight early, McEnroe took advantage of the Spaniard’s unfamiliarity with the surface.

McEnroe, sliding his first serve in consistently and volleying as well as ever, lost his serve only once and broke back the next game. For moments in an overwhelming third set, McEnroe looked like somebody who could lead anybody’s Davis Cup team for another decade.

“Yeah, that’s what happens when you get old,” McEnroe said. “It’s just moments. It used to be like that all the time for me. I felt at the top.”

Gilbert wasn’t, but he was good enough to trip Sanchez by beating him to the net, returning Sanchez’s serve well, and powering away with his slam. Spain had hoped that Sanchez, ranked No. 12 in the world, could steal the match from the better grass-court player, opening things up for a competitive final two days.

Gilbert took the first set with two service breaks, then pulled away from Sanchez in a tough second set, breaking Sanchez at 4-4 then serving out the set.

“After it was 4-all, the next two games really were the match,” Gilbert said. “I felt when I was up two sets, I was in really good shape. I felt he didn’t think he could come back from two sets down on grass.”