Watch: Gauff's improbable volley spins right into US Open umpire's chair

NEW YORK -- Reigning US Open champion Coco Gauff added her entry for Shot of the Week with a perfectly struck forehand volley winner in her second-round win over Tatjana Maria on Tuesday night. 

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Making her night-session debut on Arthur Ashe Stadium, Gauff dropped just four games to the crafty German, who worked tirelessly to force Gauff into protracted all-court rallies throughout their 80-minute duel. The match-up forced Gauff to show off her improvisational skills, and her stab-volley winner in the late stages of the first set was precisely that. 

Looking to serve out the opening set at 5-4, deuce, Gauff was drawn into the net by Maria's short-slice return. Gauff responded with a slice approach of her own, but the ball landed right in Maria's strike zone. The German unleashed a one-handed backhand drive down the line, which Gauff lunged to cover. 

Her agility paid off. Gauff popped up a response with such wicked sidespin that the ball landed just inside the sideline and careened into the umpire's chair and out of Maria's reach. 

Watch the crazy point below:

Gauff went on to close out the set and secure a 6-4, 6-0 win to set up a tough third-round challenge against Elina Svitolina. 

After the match, Gauff went straight to the practice courts to work on her serve. After striking 10 aces and serving at 64 percent in her first match, she struck nine double faults against Maria and served at just 44 percent. 

"Obviously I didn't serve great at all," Gauff said. "I got lucky. I think I only got broken once, but probably could have, should have gotten broken a couple of more times. So I just hit serves. Off the ground I felt fine."