Robin Graham steered Mr. O'Brien through the gap and off the Pimlico dirt course onto the path that leads to her barn on the racetrack's backstretch. Prancing and tugging at the reins, the 5-year-old chestnut gelding looked full of vinegar after his final workout before a run in the $1.5 million Breeders' Cup Mile on Saturday at Lone Star Park.

He acted like he wanted Graham to let him go around again.

Although a trainer, Graham, 48, of Ellicott City, likes nearly complete control of her operation, so -- as an accomplished rider -- she exercises all her horses herself.

"Great," was all she told owners Willie White and Lou Rehak, who waited by the barn entrance to find out how Mr. O'Brien went last Saturday, the day before he took a van up to Farmingdale, N.Y., and boarded a transport plane bound for Grand Prairie, Tex.

Mr. O'Brien joins Sprint long shot Abbondanza as the only representatives from Maryland in the championships. Graham is one of only two female trainers competing in the event.

A self-described worrier, Graham nevertheless appears relaxed and focused going into the biggest race of her life. She says being a perfectionist soothes and masks her nerves.

"I worry, but I've done what I have to do," she said, taking a late-morning break in her small, spartan office in the barn. "That's one of the things about doing the best you can all the time. You don't have to worry you should have done something more. An owner said to me once, 'Don't you ever get excited about your races?' If I did, the horse would pick it up."

Graham had a long stretch working for trainer Barclay Tagg, of Funny Cide fame, that ended in 1989. Since going out on her own, she has had some success locally, training 1997 Maryland Million Turf winner Trump Mahal, 2000 Maryland horse of the year Gin Talking, and the elegant multiple stakes winner Richetta. Mr. O'Brien, however, has taken her to more rarified precincts.

Graham is Mr. O'Brien's third trainer, but under her the Irish-born gelding has blossomed, winning the historic Dixie Stakes this spring before making a succession of terrific runs in top stakes -- the Manhattan Handicap at Belmont Park, the United Nations Handicap at Monmouth, the Arlington Million and a victory in his most recent start, the Grade II Kelso Breeders' Cup Handicap at Belmont.

Now Graham will ask Mr. O'Brien to make his biggest run, in the Breeders' Cup Mile on the grass. After a year in which the horse earned $514,060, Mr. O'Brien's owners put up the $135,000 nominating fee to get them into the race, which will feature some of the best turf specialists in the world.

On Wednesday, Mr. O'Brien drew the difficult outside post in a 14-horse field and was given odds of 8-1. Nothing to Lose, trained by Bobby Frankel, is favored at 7-2 and defending champion Six Perfections is next at 5-1.

"We thought he has a legitimate shot," said White, who with Rehak purchased Mr. O'Brien as a 2-year-old for $60,000. "We've been trying to get this kind of horse. People go to Kentucky and pay $300,000 for this kind of horse. Why not?"

The only time Mr. O'Brien ran poorly this year was two races back when he finished last by 21 lengths in the Shapiro Memorial Breeders' Cup Handicap at Pimlico. The race was taken off the turf because of poor conditions, and although the horse likes to run on a sloppy track, the Pimlico dirt dried rapidly after a rain before the race.

"When he got to the three-eighths pole and started to quit, [jockey] Ramon [Dominguez] let him, which was good," Graham said. "The horse was saying, 'I'm smarter than you; I don't belong on this dirt.' There's a major difference in this horse when you're on him and he steps on the turf course. He feels immediately different. You don't need the reins to communicate with him. He'll go whatever speed you want him to go. How? I don't know.' "

Before a gallop on the Lone Star track this week, Graham sat on Mr. O'Brien without even holding the reins, showing complete confidence in his disposition. The outside post has often spelled doom in the mile, with its short run to the first turn, but Graham hopes jockey Eibar Coa can somehow keep Mr. O'Brien out of trouble and let the horse do the rest.

"He just has to get him clear and let him run," she said.

Breeders' Cup Notes: Abbondanza, also to be ridden by Coa, drew the No. 6 post for the $1 million Sprint and was installed at odds of 50-1.

There is no question Abbondanza is torridly fast, but whether he can compete with some of the best sprinters in the country -- Midas Eyes, Speightstown and Champali -- remains to be seen.

"I've been through the race, and there are a few horses I think we should beat, a few I think we could beat and a few we'd have to run our lifetime best to beat," trainer Tim Tullock said. "The three [critical elements] are the break, are you good enough and staying out of trouble. I love my horse. Three-year-olds have done well in the sprint."