Spectacular Bid returned to the scene of his defeat in the Belmont Stakes and atoned for it in magnificent fashion today.

He won the $300,000 Marlboro Cup by five lengths over General Assembly and left Coastal, his conquerer in the Belmont, another 1 1/4 lengths behind. He established without doubt his supremacy over the other members of his generation. Only the 4-year-old Affirmed, who defected from today's race, stands between him and the Horse of the Year title.

Spectacular Bid's performance was a smooth and efficient one, a marked contrast from the eventful journeys he endured with the inexperienced Ron Franklin on his back in the Triple Crown races. Bill Shoemaker rode him today, and wasted no time demonstrating his astuteness.

General Assembly and Star de Naskra had broken sharply and were racing on the lead, as expected, but they were setting a very slow pace, covering the first quarter mile in a dawdling 24 2/5 seconds. Shoemaker recognized this immediately, and knew that Bid couldn't afford to hang behind the pacesetters.

"It looked like nobody wanted the lead," the 48-year-old rider said. "I knew they were going slow enough that it wasn't going to hurt him to be up there."

Bid stayed close as the front-runners covered the half-mile in 47 2/5 seconds and them picked up the tempo to go six furlongs in 1:11. Star de Naskra was the first casualty as the pace increased. The Maryland-based colt had won his last six races but he was out of his element today and he dropped from competition quickly.

Now General Assembly looked like the only rival who could give Bid a fight, but Shoemaker knew otherwise. "At the quarter pole," he said, "everybody was whipping and driving and I hadn't even asked my horse to run." As Bid accelerated through a fourth quarter in 23 1/5 seconds, he drew away with ease from the colt who had looked so awesome winning the Travers Stakes by 15 lengths last month.

Shoemaker tapped his mount only once through the stretch as he covered the 1 1/2 miles in 1:46 3/5, excellent time over a track still somewhat slow from rain earlier in the week. General Assembly held on for second over Coastal, who rallied ineffectually up the rail. Following them were Cox's Ridge, Text and Star de Naskra.

Spectacular Bid paid $3, $2.60 and $2.10. General Assemboy returned $3.40 and $2.20 and Coastal $2.40 to show.

The victory was both a relief and a vindication for trainer Bud Delp, who had been under intense pressure since Bid's loss in the Belmont. Delp said the colt had stepped on a safety pin on the morning of the race, causing his defeat. He not only had to bear the criticisms of people who said this was a cheap alibi, but he had to cure the infection in Bid's foot and get him back into peak condition in time for the Marlboro Cup.

It became obvious he had done that when Bid won a prep race at Delaware by 17 lengths. And today's race certainly verified Delp's insistence that the Belmont was not a true performance by his horse.

"This is my biggest thrill today," Delp said. "I'm just sorry Affirmed didn't run."

Affirmed had bypassed the race because trainer Laz Barrera did not like the weights that handicapper Lenny Hale had assigned. Barrera knew that on Sept. 22, in the Woodward Stakes, Affirmed would be carrying 126 pounds to Bid's 121. He thought it would be too difficult for Affirmed to carry 133 pounds and spot Bid nine in the Marlboro.

Barrera's decision to skip today's race was widely denounced as being unsporting. But given the way Spectacular Bid ran, it was surely prudent.