Libertarian closed with a rush to snatch second by a short head over Galileo Rock while Battle of Marengo finished fourth.
The favorite, Dawn Approach, was unruly through the early stages of the race, leaving jockey Kevin Manning with little choice but to let him make the lead halfway through. When the real running started, Dawn Approach was at the end of his day. He quickly faded from contention, finishing last of the 12 starters. He was undefeated in seven previous starts.
Ruler of the World, a Galileo colt making just his third career start, came into the race off a win in the Group 3 Chester Vase. He headed a group of five Derby starters trained in Ireland by Aidan O'Brien. He finished in 2:39.06 under jockey Ryan Moore.
"It was a very tactical race," Moore said. "I had a handyish spot and he quickened up impressively. He got there very quickly and easily."
Also on Saturday's card, St Nicholas Abbey, another O'Brien charge, won the Group 1 Investec Coronation Cup for the third straight time, beating Dunaden by a commanding 3 3/4 lengths. Joshua Tree was third, followed by Chapter Seven and Chamonix in a short field. St Nicholas Abbey, with Joseph O'Brien aboard, ran 1 1/2 miles on good to soft going over the Downs in 2:37.76. The world traveler picked up his sixth career Group 1 victory -- a list that also includes the 2011 Breeders' Cup Turf and this year's Dubai Sheema Classic at Meydan.
Talent sprung the surprise in the Group 1 Investec Oaks Friday, exploding through the final furlong to get home first by 3 1/4 lengths over Secret Gesture, a fellow denizen of the Ralph Beckett barn and the better fancied of the pair. The Lark finished third while Moth was fourth and Liber Nauticus fifth. Talent, a daughter of New Approach, won for the third straight time but was making her first appearance in a Group race. She finished 1 1/2 miles over good to soft going in 2:42.00 under Richard Hughes.
Gregorian came to the lead in the final furlong in Friday's Group 3 Investec Diomed Stakes at Ascot and was home first by 1 1/2 lengths over Penitent. Gregorian, a 4-year-old, Irish-bred colt by Clodovil, has been a consistent money-maker for his owner, Princess Haya of Jordan, with four wins, three seconds and a third from 13 starts.