For a fleeting moment today, when Dr. Carter surged to the lead on the turn with Time for a Change chasing him, the Donn Handicap looked as if it would be the great head-to-head confrontation that everyone at Gulfstream Park had hoped to see.

But then an undistinguished, humbly bred 53-to-1 shot named Mo Exception surged past the leaders to score a shocking upset that spoiled the comeback hopes of the two favorites.

Mo Exception won by 1 1/4 lengths over Dr. Carter, with Key to the Moon third and Time for a Change fourth.

The $125,000 race had been billed as "The Great Rematch," bringing together the one-two finishers in last year's stirring Flamingo Stakes at Hialeah. Both horses were subsequently felled by illness, and both launched comebacks here this winter. But, obviously, neither has come all the way back.

The Donn seemed to set up perfectly for the favorites when three speedsters went out to battle for the lead, setting a swift pace, while Dr. Carter, Time for a Change and Key to the Moon sat in the second flight.

As the field approached the final turn, Jorge Velasquez suddenly drove Dr. Carter up the inside to open a clear lead. J.D. Bailey followed by moving Time for a Change on the outside and drew within a length of the leader on the turn, as the crowd of 20,320 let out a roar in anticipation of the stretch duel they had come to see. Then, Key to the Moon accelerated to chase them both.

The pace was fast -- the leaders went the first three-quarters of a mile in 1:10 2/5 -- and, in retrospect, it seems all of the jockeys may have moved a bit hastily. But veteran Bobby Breen had been biding his time on Mo Exception.

"I was last down the backstretch," Breen said, "but I wasn't worried. I started to move on the turn and at the three-eighths pole I knew I was going to win. I had plenty of horse under me."

Mo Exception saved ground around the turn, drove between the leaders and had command of the Donn in the middle of the stretch.

Mo Exception, a Florida-based colt whose last major victory came in the Sunny Isle Handicap at Calder, paid $108.80, $22.60 and $7.60. Dr. Carter returned $5.20 and $3.80, and Key to the Moon paid $4.60 to show.