(Photo credit: David Frerker-Imagn Images)

The title of world's top thoroughbred racehorse in 14 difference categories will be on the line when the scions of the sport converge for the 42nd Breeders' Cup World Championships Friday and Saturday at Del Mar Thoroughbred Club just north of San Diego.

All 14 of the races -- to be contested both on dirt and turf, from as short as five furlongs to as long 1 1/2 miles -- are Grade 1 events and carry a purse of at least $1 million. Eight horses with previous Championship weekend victories to their credit are back to attempt to add to their accolades on Saturday, when nine of the races, all for 3-year-old horses or older, will be run.

Friday's five Championship events will be for juvenile horses, those 2 years of age, and are highlighted by the Juvenile and Juvenile Fillies, a pair of $2 million competitions.

The marquee event of the championships -- the $7 million Classic, which will be run on Saturday at 1 1/4 miles on the dirt -- lost top contender Sovereignty on Wednesday to the effects of a fever. Sovereignty, this year's Kentucky Derby, Belmont Stakes and Travers Stakes winner, was installed as the early 6-5 favorite in the field of 10 horses but spiked a fever on Monday after being transported from the East Coast and was scratched in a cautionary move.

'When it comes to something like this, it's just bad luck,' said Bill Mott, Sovereignty's trainer. 'You've got viruses and bacteria floating around in the air and for whatever reason, his immune system didn't battle it off. We would have loved to run, we'd love to showcase our horse. We were all anxious and excited about the opportunity to run.'

The Classic is the richest of the weekend's contests and will now send nine horses to the post; it is still expected to be the most contentious edition of the race in decades.

Defending champion Sierra Leone, the winner of this year's Whitney Stakes (G1), heads the Classic field that also includes Fierceness, who won the Pacific Classic (G1) at Del Mar in August; Preakness Stakes (G1) winner Journalism; Japanese champion Forever Young, who won the $10 million Saudi Cup in February; and Antiquarian, the winner of the Jockey Club Gold Cup (G1) in his most recent race.

'(Sierra Leone is) doing great, and (Saturday's) work was as good or better than he's worked all year,' said Chad Brown, Sierra Leone's trainer. 'He's coming into the race like last year -- very well -- and he's been working great over the past few weeks. I didn't think it was possible to build off the last two works, but he somehow managed to even work a touch better. He's really in good form.'

The $5 million Turf, to be run at 1 1/2 miles on the turf as the co-main feature on Saturday's program, will feature Irish-bred, Godolphin-owned Rebel's Romance, who will try to win the race for a record third time. The 7-year-old gelding won the Grosser Preis von Berlin (G1) in Germany in his penultimate appearance prior to this race and has captured 20 of his 29 lifetime races while earning almost $14.5 million.

'Most horses are retired at the age of 3 or 4, and it just goes to show that there's still a lot of maturity going on at that stage of their careers,' said Charlie Appleby, Rebel Romance's trainer. 'We never get to see the fully developed racehorse. We've been very fortunate to have him still here, and he's a beast of an animal going around there.'

Saturday's program includes the $2 million Distaff, the $2 million Sprint, the $1 million Filly & Mare Sprint and the $1 million Dirt Mile (all on dirt) as well as the $2 million Mile, the $2 million Filly & Mare Turf and the $1 million Turf Sprint (all on the grass).

The Todd Pletcher-trained duo of Ted Noffey and Tommy Jo will be the prohibitive favorites in the Juvenile and Juvenile Fillies, respectively, that anchor the 'Future Stars Friday' card on Halloween.

'They're doing well and I'm happy with everyone at the moment,' Pletcher said of the pair. 'We're blessed to have the opportunity to train two 2-year-olds like this.'

Friday's program will also offer the Juvenile Turf Sprint, the Juvenile Turf and Juvenile Fillies' Turf, all worth $1 million and contested on the track's Jimmy Durante Turf Course.

--Field Level Media