Always game Grey Swallow, upset winner of the Irish Derby (Ire-I) last year, returned to The Curragh Sunday to surprise again, defeating French star Bago by three-quarters of a length in the Tattersalls Gold Cup (Ire-I).Making his seasonal debut for trainer Dermot Weld, Grey Swallow, a 13-2 shot ridden by Pat Smullen, made his winning bid more than a quarter-mile from home. He hit the front early and dug deep to hold off Bago, who counts last year's Prix de l'Arc de Triomphe (Fr-I) among his five group I French victories.Bago, the 9-10 choice, lost ground reaching the straight and could not make it up in time. He was one length in front of Ace with unlucky Azamour a neck back in fourth.Smullen was celebrating his 28th birthday Sunday."That was an exceptional battling performance," Weld told Racing Post. "Pat gave him a brilliant ride. As an Irish Derby winner we decided the right thing to do with him was to put it up to the others early in the straight and that plan was executed to perfection."Grey Swallow is braveand tough as well as being talented. He did get a bit tired towards the finish but that was understandable."Weld said Grey Swallow could be destined for the United States for a fall campaign."There is a lot to look forward to with him and beating some of the best horses in Europe in a strongly contested group I was a great way to start," the trainer said.Jonathan Pease was not concerned about Bago's defeat, saying, "He just didn't quite pick up on the ground. He got himself into a hole. It's disappointing to lose but we're still very much in the game for races like the Arc and the King George."Smullen and Grey Swallow underwent a steward inquiry for floating right after taking the lead from Ace. Thierry Gillet, aboard Bago, was also warned after ducking right in the final furlong. Mick Kinane, aboard Azamour, complained that he was shut off and had no where to go. However, there was no change made in the order of finish.