Coco Gauff hailed Sun Xinran's maturity after she defeated the teenager in straight sets at the China Open.

It was a harder match than the scoreline would suggest for Gauff, who was pushed all the way before clicking into gear in the second set.

Gauff eventually reeled off nine of the final 10 games to pull away from her 16-year-old opponent and prevail 7-5 6-1.

"I think she's a little bit more mature than I was at 16," Gauff said of Sun. 

"I got a little bit more frustrated than she did. But she's an incredible player. I knew going in it was going to be a tough match. The junior career that she's had is incredible, and obviously she's going to do great at this level.

"I think this is the first of many matches on this court and many matches that we will play against each other. I'm looking forward to the future matchups we have."

125 - Since 1990, Coco Gauff (125) is now just the second player to achieve 125 career Tier I/WTA-1000 match wins before the age of 23, along with Martina Hingis (154). Milestone. #ChinaOpen | @ChinaOpen @WTA https://t.co/RbcXeZyQJ0

— OptaAce (@OptaAce) October 5, 2026

Only Hingis ahead of Gauff 

Gauff may have been around on the WTA Tour for seven years, but the American is still only 22 herself.

And while she was impressed with Son, who is six years her junior, Gauff has now hit 125 match wins at WTA 1000 events.

Since the format's introduction in 1990, Gauff is just the second player to hit that milestone in her career before turning 23, after the great Martina Hingis (154 match wins while aged 22 or under).

Gauff has now won 24 of her 28 career matches against players who are younger than her, while her sole defeat to a teenager during this time came against Victoria Mboko in Montreal last year. 

Elise Mertens is Gauff's next opponent in the round of 16, after the Belgian overcame Jelena Ostapenko 6-2 3-6 6-3.