by a neck

By an extremely short or slim margin (of distance, time, or another measure). The race was close till the very end, but Sally won it by a neck. They're just about to close the gates! It looks like we made the flight by a neck. Ah, she lost the gold medal by a neck when her leg cramped in the last few meters.

by a ˈneck

if a person or an animal wins a race by a neck, they win it by a short distance: The final was very close, with Molina finally winning by a neck.