At least part of tonight's feature race at Rosecroft is very predictable. When the field passes the stands for the first time, track announcer Billy Perkins will call the names of seven horses, pause for an instant before he mentions the last-place horse and then say, in an exhortatory tone, "Come On, Fred!"

What will happen after that is problematical. Come On Fred may accelerate and make a whirlwind finish of the sort that has established him as one of the best harness horses in Maryland. Then again, he may not. He may just stop in his tracks and refuse to finish the race. He may turn around and head back to the barn. He may do any of the things that have established him as one of the most unpredictable, idiosyncratic harness horses in creation.

In his career, Come On Fred has won nearly 50 races, earned $267,396 and paced a mile as fast as 1:56 4/5. But he has also failed to finish some 15 of his starts. His behavior in this, his 8-year-old season, has been typical. Earlier in the season, he won four straight races at Freestate against tough competition. In possibly the best form of his life, he went to Brandywine, where he pulled himself up and refused to finish either of his next two starts.

Such behavior makes Bob Uebel feel as if he is Fred's psychiatrist as well as his trainer and driver. He has been trying to understand the pacer for years.

"When Fred was a 2-year-old we had a tough time getting him to do anything," Uebel said. "But when he was 3, we realized he had a lot of speed." He also realized that Fred had a lot of idiosyncrasies, and tried to adapt his training methods to the horse's temperament.

"You absolutely can't hit him with the whip," Uebel said, "or he'll just stand there and kick the job cart to pieces. So we've used a metal leaf rake, and raked it over his back; the noise will make him go."

Not only is Come On Fred one of the few standardbreds who trains with a leaf rake, he is one of the few who trains with a pickup truck. One day, Uebel was having trouble making Fred exercise on the track at his farm, when one of the farm hands drove in their direction in a truck. That got Fred going. "That was one of those things you stumble across," Uebel said. Now Fred regularly trains with a truck behind him.

Fred also used to be a bad traveler when Uebel would van him from the farm to a track. "He'd always kick and rock the trailer," Uebel said. But once he sent Fred to the track in the company of Bob's Pepper, a 7-year-old mare, and Fred promptly settled down (even though, being a gelding, he could entertain no thoughts of hanky panky). Now Fred always travels with a companion.

Even with all these accommodations, Come On Fred has not become any less erratic on the track. On his good nights, he can do remarkable things. Uebel still remembers a minor race at Ocean Downs last year when Fred was 10 lengths behind the leader after three quarters of a mile. "I was thinking, 'This is one of those nights.' You wouldn't have given a dime for his chances. But at the three-quarter pole he just caught another gear and paced the last quarter in 27 seconds or so and won."

Fred is equally capable of subjecting his driver to some excruciating torment. This year, he was competing in a five-horse race at Freestate, which for any other horse would be a sure thing, since the first five finishers all would collect a piece of the purse. Fred came to a dead stop 30 feet from the wire, looked at the crowd, turned around and went back to the paddock.

How Come On Fred will perform in the $10,000 Pete Shaw Invitational--named for Rosecroft's general manager, who is leaving the track after 19 years--is, therefore, anybody's guess. Uebel points out that the horse will probably be hindered by his six-week layoff from competition and his No. 8 post position, but he also knows that such rational considerations are almost irrelevant where Come On Fred is considered. "This horse," he said, "can beat just about anybody--if he wants to."