Luca eyes Ebor after win.
It was the slightly more fancied Sanbuch at 13-2 who led home his stable mate Bauer (9-1) by half a length in the Detica Summer Handicap but it may be the runner-up who will bid to follow in the Knavesmire hoofprints of Purple Moon.
Meanwhile Sanbuch was providing one leg of a 123-1 treble for Ryan Moore, who also captured the Betfair Gordon Stakes on Conduit (1-2 favourite) and the Bank Of Scotland Investment Service Stakes aboard Gulf Express (10-1).
However, Cumani warned: "Bauer will go to the Ebor for sure but with a 4lb penalty Sanbuch may have put himself out of proceedings. We'll have to see.
"Sanbuch has lots of talent and we put the blinkers on today to make the horse travel a little better.
"I was really pleased with Bauer as he had not been in the best of form in the spring."
Bauer is now the sponsors' 7-1 favourite for the Ebor.
The Group Two Betfair Cup went the way of Paco Boy.
In a seven-race career Richard Hannon's colt has only encountered defeat on two occasions, firstly on his racecourse debut and also on his most recent outing in the French 2000 Guineas.
Back to seven furlongs here, he took a prominent position under Richard Hughes and the 7-1 chance showed a generous turn of foot to join Stimulation inside the final furlong, passing the post a neck in front but looking to have a little more in hand.
Hannon said: "I was a bit worried when I saw him so close at the top of the hill as normally he comes with a rattle. He got in all sorts of trouble in France - they just all closed in on him, and instead of running at Royal Ascot we just kept him for here. He has all sorts of options now."
The disappointment was 5-4 favourite Infallible, who could manage only fifth under Moore.
The jockey reflected: "She has had a busy time of it running in the Nell Gwyn, Guineas, Coronation and Falmouth - maybe that is what it was."
Marcus Tregoning has only just made double figures in winners for the season but Finjaan (5-1) ensured some optimism for the future by gamely heading off Hannon's Bonnie Charlie in an exciting renewal of the Betfair Molecomb Stakes.
"This is a great track and I took Sir Percy here when he was my best two-year-old," said Tregoning.
BOY RACER: Paco Boy ridden by Richard Hughes (in red) wins the Betfair Cup yesterday