SARATOGA SPRINGS, N.Y. (AP) -Quality Road will try to strengthen his challenge to undefeated mare Zenyatta for Horse of the Year honors in the $750,000, Grade 1 Whitney Invitational Handicap on Saturday at Saratoga Race Course.

The Todd Pletcher-trained 4-year-old is a prohibitive 2-5 morning line favorite on the strength of Grade 1 victories in the Donn Handicap at Gulfstream Park and Metropolitan Handicap at Belmont Park. He is undefeated in three starts this season and broke his own course record at Gulfstream in the Donn.

A victory in the 1 1/8-mile Whitney will put Quality Road in position to threaten 17-for-17 Zenyatta, who faces a weak field of females on Saturday in the Clement Hirsch Stakes at Del Mar.

``I think he certainly belongs in any conversation about the best horse in training,'' Pletcher said. ``I think if you look at his Donn, for example, that was just an unbelievable performance, and then to come back and turn in a similar performance in the Met. We believe he is the best horse in the country.''

Stephen Foster Handicap winner Blame and Mine That Bird, winner of the 2009 Kentucky Derby, are the most accomplished of five who will oppose Quality Road and rider John Velazquez.

The late-developing 4-year-old Blame, winner of both his 2010 starts, is trained by Albert Stall and will be ridden by Garrett Gomez. Though less ambitiously campaigned, he has a career record of 7-for-10 and never worse than third, identical to Quality Road's.

``We feel like we're ready and the time to catch the best horse in the country is when we're at the top of our game,'' Stall said.

Mine That Bird, without a victory since his 50-1 Kentucky Derby surprise, is trained by D. Wayne Lukas, who said he expects a change in running style. Mine That Bird has always raced well behind the early pace. Calvin Borel will be aboard.

``We don't have any grandiose idea that we can run down Blame or Quality Road or some of these others from left field,'' Lukas said. ``We've been training a little bit different and he's showing a bit more turn of foot, so we won't be as far back, hopefully.''

Completing the field is Musket Man, runner-up to Quality Road in the Metropolitan Handicap; Haynesfield, winner of four straight but untested in Grade I company; and Jardim, a Brazilian import without a victory in the U.S.