Sir Mark Prescott's Worthadd had to settle for second place in the Group Two Grosser Preis von Audi Zentrums Hannover on Sunday.
The ex-Italian runner had got off to the perfect start for his new connections in Baden-Baden in May but a return to Germany failed to reignite his season.
Sine his facile victory in the Badener Meile, the five year-old had been turned over at odds-on at Epsom when looking ill at ease on the track before trailing home in last place in the Queen Anne Stakes at Royal Ascot.
Partnered for the first time in his career by Jean-Bernard Eyquem, he was expected to take the beating in the mile contest but Sir Oscar, who had finished over two lengths behind Worthadd in May, reversed the form under Adrie de Vries.
Amarillo, second to Caspar Netscher in the German Guineas on his penultimate start, finished third with Saeed bin Suroor and Silvestre de Sousa out of the places with Sandagiyr.