Home advantage in California will again give the Americans the edge on dirt, but the raiding party from Britain, Ireland and France will be as strong as ever in the turf races.
Unbeaten US three-year-old Shared Belief is the firm favourite to claim the richest prize on offer in the closing Breeders' Cup Classic over one mile and two furlongs on the artificial surface on Saturday.
Jerry Hollendorfer's gelding will be bidding for a third straight Grade 1 victory after strong-running wins at Del Mar and this track on his last two starts.
However, the romantics will be hoping California Chrome can rediscover the sparkle that saw him go close to Triple Crown glory earlier this year.
The Kentucky Derby and Preakness hero faltered in the final leg when only fourth in the Belmont Stakes, but connections believe he is back to his best.
"He's training like his old self," said veteran handler Art Sherman. "I'm really pumped up. I just know that you haven't seen the real California Chrome since he was on that winning streak."
European raiders have a great record on grass at this two-day festival, though, and Toronado could be the top trans-Atlantic tip in the Breeders' Cup Mile.
Richard Hannon's ultra-consistent four-year-old was a Group 1 winner at Royal Ascot and has since finished a rock-solid runner-up to Kingman at Glorious Goodwood and Charm Spirit in the Prix du Moulin at Longchamp.
With America's big hope Wise Dan ruled out here, the dangers also travel across from Europe, including Ireland's Mustajeeb, plus Veda and Anodin for France.
Five of the last six Breeders' Cup Turf victors have hailed from Europe and there is another powerful challenge in this 1m 4f contest this term.
Prix de l'Arc de Triomphe runner-up Flintshire and Royal Ascot scorer Telescope head the market, but Aidan O'Brien will also send over defending champion Magician for a repeat bid.
The Breeders' Cup Filly and Mare Turf has been another happy hunting ground for Europe and Sir Michael Stoute is eyeing a second straight success with Dank, who was a cosy winner 12 months ago.
Friday's fare is very much the appetiser in this feast of top-class racing, but the Breeders' Cup Juvenile Turf features a strong European challenge, including O'Brien's War Envoy, who has held his own at the highest level on several occasions.
However, Wesley Ward's Hootenanny impressed in trips across to Royal Ascot and France over the summer and will be a tough nut to crack back on his own patch.
And if there is to be a gatecrasher from the rest of the world, Hong Kong-based speedster Rich Tapestry is already a Grade 1 course winner this month and will be well fancied for Saturday's Breeders' Cup Sprint.