5/4 favourite Circus Maximus led home an Aidan O'Brien one-two in the Homeserve Dee Stakes at Chester.
24 hours earlier Sir Dragonet and Norway had dominated the other major Investec Derby trial of the meeting, the Vase, for the Ballydoyle team and they always looked to have this prize in safe keeping.
The winner tracked the leader Allmankind throughout the contest and was kicked to front on the final turn by Ryan Moore.
The two lengths advantage he took there was crucial as Mohawk (7/1) closed him down inside the distance but could never land a telling blow.
Fox Chairman was strong in the market beforehand and finished well to take third for Andrew Balding and Silvestre De Sousa having been caught on the heels of rivals turning in.
Sky Bet cut the winner to 16/1 from 25/1 for the Epsom Classic. Racing PR Manager Michael Shinners said: "Aidan's Investec Derby hand is strengthening by the trial but Circus Maximus might just be a little down the pecking order right now."
O'Brien said: "You would be delighted with the two of them, they were two lovely runs. The two of them were in the Guineas up to the last stage. You would always prefer better ground, but it was good they went through with it.
"He (Circus Maximus) is a relaxed horse and just needed to learn a little bit, so it was lovely to come here. He got a lovely, handy break as he can get lazy in his races and he dropped back, then Ryan moved him up and he came back on the bridle. Ryan said in an ideal world he would have preferred to have a lead for a little while longer, but you couldn't be happier.
"The great thing about here is that they have to have quick feet and they have to learn to jump, travel and keep going. The ground was slow, so he had to work a bit harder."
O'Brien was speaking 24 hours after seeing Sir Dragonet bolt up in the MBNA Chester Vase - and hinted that the son of Camelot could be supplemented for the premier Classic, for which he shot to the forefront of in the ante-post market.
He said: "The lads will decide want they want to do, but it is very possible (supplementing for the Derby). It's great, as we have time decide, but you couldn't be more impressed.
"I don't think he needs soft ground. He is a lovely, well-balanced horse - it has just been that he has run well on soft ground twice. He obviously has a massive engine."
Balding, meanwhile, said of Fox Chairman: "Silvestre (de Sousa) said he was slightly inconvenienced by the softer ground, it was a bit softer than he had to encounter at Newbury and he lost his pitch.
"He stayed on well and learned plenty for it. He has finished well and just got caught on heels at a vital stage, but I don't think the end result would have been any different. He is a lovely horse and we will go to Ascot, probably for the Hampton Court."