WHAT HAPPENED: Anett Kontaveit of Estonia is taking full advantage of her very first US Open, extending her winning streak into the round of 16. The 19-year-old, who came through the qualifying rounds, defeated 25-year-old American Madison Brengle in her third-ever main-draw match, 6-2, 3-6, 6-0.

Kontaveit, currently ranked No. 152 and so unlikely an advancer that "Photo not available" accompanies her stats, came out swinging, with 16 winners in the first set and a first-serve points-won percentage at a lofty 85 percent. Brengle found her range in the second, getting the early break to go up 4-1, despite long points and games.  

While serving for the set at 5-3, Brengle fought off two break points and took the momentum for the 6-3 win, but frustration came over her when Kontaveit immediately broke in the third set and then quickly reached a 3-0 lead. Despite some good rallies, Brengle couldn't find a way to raise her level to that of the teen's, squandering her only break chance and winning only 10 points in the set. 

WHAT IT MEANS: Kontaveit, who upset No. 31 seed Anastasia Pavlyuchenkova in the second round, has already more than doubled her 2015 earnings of $89,559 since she arrived in Flushing. In her sixth singles match in the last week, Kontaveit shows no sign of fatigue. She’s also becoming popular with the spectators. She may have a harder time winning over the audience in her next match as she’s going to be facing American Venus Williams.

THE QUESTION: Kontaveit has shown she has stamina, but can she be a threat to the rejuvenated Venus Williams?

September 4, 2015 - Anett Kontaveit in action in a women's singles third round match against Madison Brengle during the 2015 US Open at the USTA Billie Jean King National Tennis Center in Flushing, NY. (USTA/Brian Friedman)