At the buzzer
Definition 1 of 1
Pro Tip 1/3Sports Origin
Originates from basketball where a buzzer marks the end of play time. 
The crowd erupted as he hit a three-pointer at the buzzer.
Pro Tip 2/3Last Moment Action
Used to describe an action occurring right before a deadline or time limit expires. 
She submitted her exam paper at the buzzer.
Pro Tip 3/3Tense Atmosphere
Implies a tense or thrilling moment, often with a crowd watching. 
With everyone's eyes on him, he scored at the buzzer.