They are The Great Entertainers of our time. Affirmed and Alydar. There's even the flavor of 1920's vaudeville in the linkage of their names.

Oh, better races have been run, I guess, than the show these two thoroughbreds put on yesterday in the 110th Belmont Stakes. Jaipur beating Ridan by a nose at the end of a 1 1/4-mile, Travers at Saratoga comes to mind. That was a match from flagfall to finish, as the chartists say.

But the 1963 Travers was so relatively unimportant compared to the final event in the 1978 Triple Crown series. So much was at stake for Affirmed in his bid to join the 10 others that had swept the Kentucky Derby, Preakness and Belmont. And Alydar was determined to deny.

The first half-mile was an invitation to a waltz, Affirmed leading by a length in 150. Then Jorge Velasquez, on Alydar, forced Steve Cauthen to pick up the tempo. They moved up the back-stretch in :24, whirled to the far turn in :23 2/5, charged hell-bent around Belmont's sweeping stretch bend in an unbelievable :24 1/5 - and still had enough left to finish out in :25 1/5 for a 2:26 4/5, the Belmont's third-fastest running.

"What did your horse (Darby Creek Road) lose by?" Lou Rondinello was asked a few minutes after the finish.

"How do I know," the trainer replied. "I was wrapped up, like everybody else, looking at those first two."

Such is the magnestism of Affirmed and Alydar. They dwarf their 3-year-old rivals. Alydar has yet to beat Affirmed in a close finish. The last four decisions, dating to the Laurel Futurity last fall, all fall into Affirmed's victory column. But Alydar never quits punching.

For a few strides, leaving the three-sixteenths pole yesterday, it appeared as though Alydar had gained the upper hand he last enjoyed here last October in the Champagne Stakes. But no. "He plays with him, like a cat plays with a mouse," laz Barrera says of Affirmed's relation with Alydar.

That may have been true in the preakness, three weeks earlier, when Alydar won by a neck. It was not the case in the Belmont. Alydar was The Mouse That Roared in early stretch. Velasquez had forced Cauthen to switch his whip from his right to his left hand. It looked like Alydar's day . . . except that Affirmed always out-guts Alydar in these tight situations.

This was a race to be enjoyed and remembered, the end to a Triple Crown series that was without equal in terms of a two-horse rivalry.

"I went a back into the record books and checked, after the Preakness, there's never been anything like it," said Mike Barry, a columnist for the Louisville Courier Journal who has seen a helf-century of Triple Crown competition. "Never have two colts had such a long, brilliant battle." In fact, Alydar is the first colt ever to finish second in all three races to a Triple Crown champion.

There was but one discordant note. Barrera, in the press box, indicated Affirmed probably would run next in the Travers in August. Veitch said Alydar would be there, too.

Then Barrera added: "If I have my way, Affirmed will not run on the grass and he will not run against older horses this year. I think he probably is horse of the year already, and I'd like for him to run against next year, as a 4-year-old."

That would be a shame and owner Lou Wolfson will have another say in the matter. There is move afoot to have Affirmed, Alydar, Seattle Slew, Cox's Ridge, Forego and J.O. Tobin get together for a little $2,000,000 hand of pony poker before this season is over.

We can only hope Affirmed's owner and trainer now will show the same sort of courage their colt displayed this spring against Alydar.

"Affirmed will get a rest, in light training for several weeks," Barrera said.Fine, the colt deserves it. The Triple Crown, as John Veitch, Alydar's trainer, noted, is a long, tough grind.

But it is not the end of the world in achievement, in too much of the public mind. The truly championship races are run here in the fall - the Woodward, Marlboro Cup and Jockey Club Gold Cup - often under weight-for-age conditions. Affirmed should be here for them. He belongs. So does Aldyar.