Switch pays off for Observatory Observatory kicked off his four-year-old campaign in the best possible manner with a Group One success in the Prix d`Ispahan at Longchamp in France this afternoon. Re-routed from Saturday`s Lockinge Stakes at Newbury the John Gosden-trained, Richard Hughes-ridden colt collared France`s Hightori close home to prevail by a short-head. Godolphin`s Ekraar, who had set out smartly to try and make all under Frankie Dettori, was third. Gosden remarked: 'We came here because the ground was too soft at Newbury but it turned out to be too fast here. 'We decided to miss the Breeders` Cup last year as we wanted to keep him ready for a four-year-old career. He was at only 85 per cent of his best form today, and next stop will be the Prince of Wales`s Stakes at Royal Ascot.' The Khalid Abdulla-owned Observatory, last seen lowering the colours of the mighty Giant`s Causeway in the Queen Elizabeth II Stakes, will renew rivalry with Hightori at Ascot. The French colt delighted his trainer Philippe Demercastel given that he received a lengthy holiday following his tough race in the Dubai World Cup where he took third to Captain Steve. Elsewhere on the card Dominque Boeuf, the former French champion, reigned supreme, landing Group One Prix Saint Alary on Nadia and the Group Two Prix Vicomtesse Vigier on Speedmaster, trained by the versatile Francois Doumen. Both could run next in England, Nadia in the Vodafone Oaks and Speedmaster in the Gold Cup at Royal Ascot, for which he would have to be supplemented. After Nadia had prevailed in the 10-furlong Saint Alary by a head from Mare Nostrum trainer Carlos Laffon-Parias said: 'She could for either the French or English Oaks. I think she will stay. If she were to remain in France I would run her with a pacemaker.' Speedmaster came in ahead of the Andre Fabre-trained Polish Summer, ridden by Hughes.