Wimbledon champion Simona Halep was dumped out of the China Open on Monday, losing in straight sets to Ekaterina Alexandrova in Beijing.

Halep toiled throughout the encounter, eventually losing 6-2, 6-3. Elsewhere, U.S. Open winner Bianca Andreescu progressed in three sets against Aliaksandra Sasnovich.

In the men's bracket, second seed Alexander Zverev had no problems in his first match of the competition, proving too good for Frances Tiafoe. There was also a win for fourth seed Karen Khachanov over Pablo Cuevas.

Here are the latest results from the National Tennis Center and a look at some of the best action from Monday's matches.

China Open - Selected Monday Results

Women's Draw

(5) Bianca Andreescu bt. Aliaksandra Sasnovich: 6-2, 2-6, 6-1

Ekaterina Alexandrova bt. (6) Simona Halep: 6-2, 6-3

(8) Kiki Bertens bt. Dayana Yastremska: 7-6 (5), 6-3

(11) Madison Keys bt. Karolina Muchova: 6-4, 7-6 (5)

(16) Caroline Wozniacki bt. Lauren Davis: 6-1, 6-3

Men's Draw

(2) Alexander Zverev bt. Frances Tiafoe: 6-3, 6-2

(4) Karen Khachanov bt. Pablo Cuevas: 6-2, 7-6 (7)

For the full results and draw, visit the competition website.

Monday Recap

Already there have been big shocks at the China Open, and the trend continued on Monday with the elimination of Halep.

The Romanian has become renowned for her competitive edge and intensity when out on court. Surprisingly, those traits were lacking in Beijing, as the two-time Grand Slam winner was well short of her best against Alexandrova.

Per the WTA Insider Twitter account, the Wimbledon champion didn't look to have completely recovered from the back problem that prompted a retirement at the Wuhan Open last week:

Here is the moment Alexandrova secured one of the biggest wins of her career:

One of the year's other major champions, Andreescu, managed to find her way through into the next round, albeit she didn't have it all her own way against Sasnovich.

In her first match since beating Serena Williams in the final at Flushing Meadows, it was no shock to see Andreescu look a little rusty to begin with, and she struggled for fluidity in the second set. She improved as the match went on though, showcasing her trademark power in the final stages.

Speaking after the win, the Canadian said she's enjoying being in a winning groove:

Zverev will be seeking to finish his season on a high, and he was dialled-in throughout his showdown with Tiafoe.

Jose Morgado of Record suggested this was the best he had played all season, with the German carrying his excellent form from the Laver Cup into this event:

The top seeds in both draws have yet to get their China Open campaigns under way, although they'll each be in action in Beijing on Tuesday.

Ashleigh Barty will go up against Yulia Putinseva in the women's draw, while Dominic Thiem faces a potentially challenging opener against the talented veteran Richard Gasquet.