Every horse owner has the prerogative of firing his jockey, but it wasn't easy for Peter Fuller. He had to replace his own daughter before today's Selima Stakes at Laurel.

Abby Fuller had ridden the 2-year-old Mom's Command in three New York stakes, and her rides had been less than brilliant. So today Gregg McCarron got the mount, and he guided the filly to a wire-to-wire win in the $262,550 race.

Mom's Command scored by 2 1/4 lengths over Diplomette. Charleston Rag, the odds-on favorite, never got into contention and finished fourth.

Mom's Command had displayed high speed and considerable potential in her five-race career, but she was often hurt by her jockey's inability to get out of the gate cleanly.

The Racing Form comments on her last three efforts read, "Off poorly," "Poor start" and "Steadied at start." Two weeks ago at Belmont Park, she accelerated so strongly after being left at the gate that she was able to take a three-length lead, but she wound up being whipped by Charleston Rag.

"This is a free-running horse," Peter Fuller said, "and Gregg fits her better. My daughter had seven mounts at Suffolk today."

With McCarron aboard, Mom's Command was a different horse. She broke sharply and took the lead, while it was the 2-to-5 Charleston Rag who had trouble, stumbling soon after the start.

Mom's Command sprinted clear and opened a quick 2 1/2-length as she sped the first quarter in 22 4/5 seconds. "She was rank though the first quarter," McCarron said, "but, once we straightened down the backstretch, she really went well."

The leader maintained a comfortable advantage over Soliciting, the longshot who was pursuing her, then took a five-length lead on the turn. Chris McCarron swung Charleston Rag wide on the turn and tried to accelerate, but it became quickly apparent that his brother was going to be the victorious McCarron today.

Mom's Command covered the 1 1/16 miles in a respectable 1:43 3/5 and paid $36.20.

In the winner's circle, Fuller proclaimed that his filly was now the favorite to win the Eclipse Award as the outstanding 2-year-old filly of 1984. This may have been a slightly optimistic assessment, but it was not outlandish.

The current crop of juveniles is the weakest in at least a decade, and Mom's Command's victory today was as authoritative as any performance by any of her contemporaries. Besides, it can be argued, she is unbeaten for life with jockeys other than Abby Fuller on her back.