By a nose
Definition 1 of 2
Pro Tip 1/3Racing Origin
The phrase originated from horse racing, where races can be so close they're decided by the length of a horse’s nose. 
The underdog team won the championship by a nose, much like in those thrilling horse races.
Pro Tip 2/3Figurative Use
This phrase is often used figuratively to denote any narrow victory, not just in actual races or competitions. 
She won the student council election by a nose after a very tight vote count.
Pro Tip 3/3Emotionally Charged
Using 'by a nose' can convey a sense of excitement or relief from a near defeat and is ideal for dramatic storytelling. 
After months of lagging in polls, the candidate won by a nose in a surprising turn of events.