Oxford won their second consecutive Boat Race by just one foot - the closest verdict in 149 events.
In a race that saw the lead exchanged three times, Cambridge almost succeeded in pulling back from a length disadvantage around the outside of the Chiswick bend.
But Oxford, stroked by president Matt Smith, held on for their 71st victory in a time of 18 minutes six seconds, thanks to a sprint finish that saw them hit 40 strokes per minute.
The annual event has seen just one match recorded as a dead heat but that race, in 1877, saw the crews finish six feet apart.
Cambridge were forced to make an 11th-hour substitution after bow-man Wayne Pommen was injured in collision with a launch on Friday.
But they could have been forgiven for feeling they had an early edge when president Tim Wooge won the toss and selected the Surrey side of the river.
That advantage looked to be telling around the long Surrey bend as the light blues overhauled a half-length Oxford lead after a higher tempo start.
But Oxford cox Acer Nethercott steered a tenacious line, risking disqualification as blades clashed along Chiswick Eyot to ensure his rivals could not get away.
And as the bend swung back in their favour, the dark blues came though, going close to pulling clear.
Cambridge, an average of 7kg per man heavier than their counterparts, appeared sluggish by comparison for much of the race.
They almost became just the fourth crew in history to come from behind at Barnes Bridge.
But their late push proved just not enough when, after an agonising wait, the official verdict was announced.
Earlier, Cambridge's second crew Goldie beat counterparts Isis by three-and-a-half lengths in the reserve race in a time of 18m 4s - two seconds faster than their superiors.
Oxford: J Adams, B Dixon, S McLennan, D Livingston, R Bourne-Taylor, S Frandsen, H Morris, M Smith, (president), A Nethercott (cox)
Cambridge: B Smith, K Coventry, H Mallinson, M Kleinz, A McGarel-Groves, T James, J Livingston, T Wooge (president), J Omartian (cox)