O'Brien Classic talent put on show.
The Ballydoyle maestro's squad included George Washington and Rumplestiltskin, respective favourites for the Stan James 2000 and 1000 Guineas at Newmarket next month.
The former showed signs of temperament as he was cantered to the five-and-a-half furlong pole by Kieren Fallon, having proved reluctant to leave the paddock and being led on to the racecourse.
He then ducked out at a chute three furlongs from home but was noticeably better behaved on his way back in company with River Tiber.
The pair moved at a leisurely pace before George Washington eased half a length up, although O'Brien stressed the object of the exercise had been to bring them back to a racecourse with the Guineas less than a month away.
He said: "George Washington has always been that way. He has never been a docile horse and it is not a problem. It was great to bring him back to the surroundings of a racecourse and he is on course for Newmarket."
The sponsors, mindful of the signs of temperament which O'Brien puts down to arrogance, eased him from 9-4 out to 5-2 for Newmarket.
Horatio Nelson satisfied O'Brien in his work over the same distance in company with Augustus John.
He put on 55 kilos during the winter but has shed that and according to his trainer is still very much in the picture for the Guineas en route to the Derby.
Art Museum really looked the part in his work with Major Commitment as he effortlessly eased ahead of his stablemate in the final 100 yards. He was cut to 10-1 from 14-1 for Newmarket by the sponsors.
Rumplestiltskin has not grown much through the close season but there was much to like about the way she moved in company with Fermion.
The champion filly of 2005 will head straight for the Guineas but there is a question about which one.
O'Brien observed: "She has won at Longchamp but I haven't decided which race she'll go for. Race For The Stars is also in the picture for Newmarket and we shall have to see,"
Race For The Stars (Seamus Heffernan) impressed in her work with Be My Queen and was cut from 16-1 into 14-1 for the 1000 by the sponsors.
Jim Bolger worked Heliostatic, who impressively put paid to two stablemates and is in to 33 from 50s for the Derby with William Hill.