WAS THERE A tennis player in America on Sunday who did not go out on the court in the afternoon and attempt to apply the lessons learned by watching Pat Cash beat Ivan Lendl at Wimbledon in the morning? This is the great thing about tennis, which, more than any other sport, numbers among those who watch its high moments so many of those who play it as well. Especially is this so about the Wimbledon finals, whose timing allows the tennis legions of America to take to the court later the same day to emulate -- this year -- Pat Cash, the 22-year-old Australian who won his first Wimbledon, and Martina Navratilova, who took her eighth.

Miss Navratilova had gotten to the finals by beating Chris Evert in a match as memorable for the comradeship of these two valiant veteran opponents, total all-giving professionals, as for the quality of the play. The actual finals, as distinguished from the emotional finals, pitted Miss Navratilova, 30, against an 18-year-old, Steffi Graf, who will have many days but whom it was thoroughly appropriate for Martina Navratilova to beat on this day of July 4, 1987. Fortunately, she had the skill and strength to make the poetry of generational combat come out right this time.

Ranked No. 1 in the world, Ivan Lendl, 27, is known for a certain calculated mental style of play -- and for hitting, hitting, hitting. Ranked No. 413 because of back problems a year ago, Pat Cash came into the match as the brash kid Aussie who'd knocked off the game, gutsy 34-year-old Jimmy Connors. The Cash-Lendl match was terrific, but it was Mr. Cash who did the hitting, hitting, hitting, and he warmed the gallery's heart by climbing up the stands to embrace his father.

We then went out on the court ourselves, knowing at last exactly what had to be done. First, you hit an overpowering serve deep in the back corner that kicks outside and forces your opponent into the wire. In an instant you are at net to take the feeble reply and slice it effortlessly to the far corner. Then, receiving, you take the serve on the rise and slam it mercilessly down the line past the server's flailing racket. For a changeup, you hit a wicked crosscourt; your opponent never touches it and the gallery gasps. Ah, Wimbledon!