US Open Tennis 2019 Results: No. 1 Naomi Osaka Upset in Early Monday Play

The 2019 U.S. Open women's top seed Naomi Osaka was forced to pack her bags during Monday's early session, losing in straight sets to Belinda Bencic.

It wasn't the only upset of the early session, with Alexander Zverev losing to Diego Schwartzman after winning the first set.

Here are some key results from Monday's early action.

Men's Singles

(20) Diego Schwartzman bt. (6) Alexander Zverev: 3-6, 6-2, 6-4, 6-3

(24) Matteo Berrettini bt. Andrey Rublev: 6-1, 6-4, 7-6 (6)

Women's Singles

(13) Belinda Bencic bt. (1) Naomi Osaka: 7-5, 6-4

(23) Donna Vekic bt. (26) Julia Goerges: 6-7 (5), 7-5, 6-3

For the full results and playing schedule, click here. 

Bencic has been a nightmare opponent for Osaka in 2019, bagging her third win over the defending champion, per sportswriter Ben Rothenberg:

It marks the 22-year-old's second trip to the U.S. Open quarter-finals, five years after her first.

Bencic has been steadily building up her form this year, using her excellent ability to counter in rallies to great effect. Her playing style makes her a nightmare opponent for Osaka, who likes to use her power from the baseline to win points.

Their clashing style of play made for some great highlights:

With 29 winners and just 12 unforced errors, Bencic picked a great time to play some of her best tennis, and she will be a handful moving forward. She'll face Vekic in the next round, after she came from behind to beat Goerges.

In the men's draw, Schwartzman overcame struggles in the first set to beat Zverev, taking full advantage of his many mistakes on serve.

The German hit an incredible 17 double-faults, part of what was a dreadful day for the talent, per sportswriter Uche Amako:

The 22-year-old still hasn't made it past the fourth round of a Grand Slam outside of the French Open. Schwartzman will face Rafael Nadal or Marin Cilic in the quarter-finals.