Grigor Dimitrov's hopes of defending his ATP Tour Finals title suffered a major blow on Wednesday, as he was beaten by Dusan Lajovic at the China Open.

The Bulgarian, seeded third at the event, lost in three sets, and as a result he is a long way down the standings in the race to qualify for the season-ending event in London. Meanwhile, top seed Juan Martin del Potro progressed at the expense of Karen Khachanov.

In the women's draw, there were no issues for second seed Caroline Wozniacki or seventh seen Karolina Pliskova, as they both came through their matches in straight sets. 2017 U.S. Open champion Sloane Stephens is in action later in the day.

Here are the results from the Beijing International Tennis Center, the schedule for Thursday and a look at some of the best moments from the day's play.

Selected Wednesday Results

Men's Draw

(1) Juan Martin del Potro bt. Karen Khachanov, 6-4, 7-6(4)

Dusan Lajovic bt. (3) Grigor Dimitrov, 6-4, 2-6, 6-4

(5) Kyle Edmund bt. Matteo Berrettini, 7-5, 6-7(2), 7-5

Women's Draw

(2) Caroline Wozniacki bt. Petra Martic, 7-5, 6-3

(5) Karolina Pliskova bt. Aliaksandra Sasnovich, 6-3, 6-4

For the results in full visit the China Open website.

Thursday Schedule

Wednesday Recap

After finishing 2017 in such brilliant form, Dimitrov's season is in danger of fizzling out with a whimper in 2018.

In the loss to Lajovic, the Bulgarian was a long way short of his trademark best and failed to make the most of the momentum he built up in an improved second set. 

Per Jose Morgado of Record, he now needs to do something special in the final stages of the year if he's to get to London and defend the prize he memorably won a year ago:

Lajovic, meanwhile, will be delighted with his display and celebrated a deserved win over one of the world's best players:

Next up for him will be Kyle Edmund, who was given a big scare by Matteo Berrettini in a thrilling three-set match. The Briton wasn't at full tilt, yet he showed his class on the big points.

The same can be said of Del Potro, who was well matched by Khachanov, winning in two tight sets. The Russian dug deep at the end of the second to break when his opponent was serving for the match, but eventually, the Argentinian came through in a tiebreak.  

In the women's draw, it was a straightforward day for some of the big names, including Wozniacki, who is the highest-ranked player left in the draw after Simona Halep's early exit.

The Dane always looked as though she had gears to go into against Petra Martic—who she has a perfect head-to-head record against—as illustrated by the final point of the match:

Pliskova, meanwhile, turned in one of the standout performances in the women's draw so far, as she hammered 21 winners past Sasnovich to come out on top in their tussle.

The third round has thrown up an interesting match for her, too. Home qualifier Wang Qiang, who fed Jelena Ostapenko a double bagel on Tuesday, stands between the seventh seed and a place in the quarter-finals.