Island Whirl won the $173,100 Whitney Handicap by a nose at Saratoga Race Course today and trainer Laz Barrera said he thought his 5-year-old could earn the Horse of the Year title this fall.

Certainly it is possible that the best horse in America was in the field for this historic race. But racing fans may have to study the charts and the films of the Whitney to discern who it was.

Maybe it was the winner, who led all the way and fought off repeated challenges before he reached the wire an inch or so in front of longshot Bold Style.

Maybe it was Deputy Minister, who carried high weight of 126 pounds to the winner's 123, had to travel extremely wide on the turn but accelerated to finish fourth.

Or maybe it was that forgotten colt, Kentucky Derby winner Sunny's Halo, who gave a remarkably strong performance to be third, only three-quarters of a length behind the winner, even though his trainer knew he lacked the necessary preparation to win this race.

Those ambiguities will be resolved in the coming weeks, but today the glory belongs to the invader from California, who joined the list of thoroughbreds who have won more than $1 million in their careers. He may not have the reputation, consistency or versatility of some of his rivals, but he has the speed that enables him to control and dominate races like today's.

There were no other speedballs in the field brave enough to challenge Island Whirl early, and so jockey Eddie Delahoussaye was able to take the lead and set an easy pace, covering the first half-mile in 46 4/5 seconds, with Linkage stalking him from the outside and Sunny's Halo sitting just behind him on the rail.

As the field reached the turn, practically every jockey started to make his move, or at least wanted to. Sunny's Halo was briefly blocked. Deputy Minister had to swing six-wide on the turn. Star Choice was even wider. When they swung into the stretch, a hole opened for Sunny's Halo, and Bold Style found racing room without having lost too much ground.

Bold Style, a 25-to-l shot, was accelerating fast and drew abreast of the leader in the last 16th of a mile, but Island Whirl wouldn't let him get by.

"Island Whirl was getting tired in the stretch," Bold Style's jockey, Pat Day, said, "but he is a game old horse and really dug in. Another four or five jumps and I would have won."

The race, however, was not carded for 1 1/8 miles and four jumps. Island Whirl covered the prescribed distance in a respectable 1:48 2/5 and paid $4.60, $3.60 and $2.80. Bold Style returned $16.60 and $6.60 and Sunny's Halo paid $4 to show.

Barrera said Island Whirl would go to Belmont Park this fall to run in the Marlboro Cup and the Woodward Stakes. Deputy Minister will almost surely follow the same course.

Sunny's Halo has more immediate plans. Two weeks from today he will attack his main objective, the Travers Stakes. It doesn't take much probing analysis of the Whitney to conclude that he is going to be tough to beat against members of his own age group.