I've thought about this kind of scenario, bizarrely, a decent amount recently. Long story short, assuming your opponent is so strong that once you're in arms' reach, you're done, you have to be faster than said opponent not only at endurance running but also at every distance between. E.g. assuming you start off somewhat close to them, you have to sprint faster and transition into a faster endurance running pace, and at no point can you be so much slower than them at a given distance that they're able to regain any ground you made on them at a different speed.