BEIJING, China -- It's a couple of sweet sixteens for US Open champion Bianca Andreescu of Canada, as she extended her undefeated streak to 16 matches after a 6-3, 7-6(5) victory over Elise Mertens of Belgium, which sent her into the round of 16 at the China Open on Wednesday.

In a rematch of their US Open quarterfinal clash, which went three sets, No.5 seed Andreescu triumphed again after an hour and 55 minutes of closely contested action, improving her head-to-head against World No.23 Mertens to 2-0.

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In an intense battle, Andreescu continued to claim the most important points with gusto, converting five of her six break points while saving eight of the 12 break points she faced. This allowed her to erase a 1-4 deficit in the second set, as well as save a set point at 4-5. Andreescu also fought back from 1-3 down in the second-set tiebreak.

Andreescu now sets up a third-round tilt against American qualifier Jennifer Brady. World No.66 Brady upset her fellow American Madison Keys in three sets earlier on Wednesday, coming back from a set and a break down to do so. Andreescu leads Brady 3-1 in their head-to-head, although Brady won their most recent meeting last year.

The match began with both players double faulting on break point in their opening service games; Andreescu repeated that in her next service game as well, before blasting a backhand winner down the line to break Mertens again and reach 2-2.

After the inauspicious start, Andreescu recovered the shots which brought her to a maiden Grand Slam title last month, firing a forehand winner to reach break point at 3-2, which she converted for a third consecutive break of Mertens’s serve. 

The Canadian fended off a break point with a fierce forehand as she picked up a hold for 5-2, and reached triple set point two games later with a crosscourt winner from that wing. Andreescu only needed one of those set points, as Mertens netted a return to cede the opener to the fifth seed.

It was Mertens, though, who got off to a torrid start in the second set. The Belgian held three break points at 1-0, and the third of those was the charm as she blasted a backhand return winner to go up 2-0. After clinching a love hold for 4-1 and earning another break point for a 5-1 lead, Mertens was extremely close to pulling the match into a decider.

Andreescu, however, gritted out the hold for 4-2, and then earned a break point in the next game with a scintillating forehand pass down the line. After cracking a backhand to force an error, Andreescu had gotten back on serve at 4-3. The Canadian teen then won a 10-minute game to tie the set at 4-4, saving two more break points in the process.

Nevertheless, Mertens still found herself one point away from a third set, as a long forehand by Andreescu gave the Belgian set point at 5-4. Andreescu, though, won a superlative rally to erase the Belgian's chance, and the US Open champion held on for 5-5. By this point, the rallies had become lengthier and more sparkling, and the duo fought for every single shot as they steered into the tiebreak.

Another long rally gave Mertens the first minibreak, as she smacked a winner down the line for 2-1. The Andreescu forehand, though, helped pull her back from 3-1 to 3-3. More strong all-court play from Mertens put her ahead 5-4, but Andreescu clinched her next two service points, teeing up match point at 6-5. There, the Canadian fired a backhand on the baseline to force an error from Mertens, sealing the hard-fought victory.

More to follow....