The Classic Cup has produced more than its share of upsets in a brief history but it won't be the biggest shock on its honour roll if John Size-trained Sun Jewellery manages to add the second leg of the four-year-old Group One series to his record.

Size has won three of its 10 runnings - with Unique Jewellery at 11-1, It Has To Be You at 125-1 and Thunder Fantasy last year at 22-1 - but he will likely have more support on Sun Jewellery (Ryan Moore) than those previous successes.

The chestnut is looking to add the Classic Cup to the Classic Mile, when horseplayers abandoned him largely due to a doubt about him seeing out 1,600m in his first attempt.

Today, he goes an extra 200m and some of the big upsets in this race have been when horses like Lucky Nine and Beauty Flash were rolled at odds-on as the established class runners of the field who didn't stay. Sun Jewellery has a bit in common with them on that score but is entitled to the benefit of the doubt about running 1,800m and his Classic Mile win gave plenty of encouragement.

John Moore-trained Werther (Hugh Bowman) will be today's favourite based on his second in the Classic Mile, and he would have won if he'd got into clear running when he wanted it.

But it's worth noting that he had also enjoyed a soft, trouble-free run until that time, while Sun Jewellery had done a lot more work in the opening 400m to find his position from barrier 14. That made him vulnerable over the final 200m when Werther was still full of energy and, had their runs been reversed, perhaps Size's horse would have looked more commanding.

Today, Sun Jewellery comes in to gate three and the likelihood of a perfect trip on the back of the leaders, saving his petrol for the finish instead of spending it early.

Still, it would be wrong to knock Werther, who maps to get a nice run, and has no distance doubts. He sat behind Sun Jewellery in the Classic Mile, but at both runs here he has shown speed early and don't expect he will be far away from his rival today in running.

Classic Mile third Blizzard (Gerald Mosse) is also a distance doubt and without the luxury of a good draw, while others from that race have a bit to find.