Thought Worthy got the better of Noble Mission in the poptelecom.co.uk Fairway Stakes at Newmarket.
William Buick set out to make every yard in the 10 furlong Listed contest and had just enough in the tank to repel his four rivals despite being headed by Farhaan at one stage.
The Derby entry is a brother to the same connections 2007 St Leger winner Lucarno and showed plenty of his sibling's qualities in battling on to the line.
The runner-up is also the sibling of an illustrious performer in Frankel and his older brother will attempt to restore the family honour later on the day at Newbury in the Lockinge Stakes.
There were four horses in a line inside the final quarter of a mile with only Prince Alzain failing to pick up and it was Noble Mission that threw down the strongest challenge despite being one of the first to come under pressure.
Eddie Ahern's mount could never quite get there though and was a neck adrift of John Gosden's charge at the line.
Although Thought Worthy is still in contention for the Investec Derby, connections could also be tempted to run him in the Ladbrokes St Leger at Doncaster.
Gosden said: "You don't need a lot of runners to have a hell of a finish.
"He showed a lot of guts and we are very happy with him.
"He is screaming out for a mile and a half. He is still in the Derby and the owner is a sportsman - he will make the final decision.
"The King Edward VII (Royal Ascot), we could look at that, and the owner likes that race on Town Moor (St Leger) in the middle of September as well.
"He will have one more run and we will then freshen him up."