Shang bests Shelton to reach ATP Washington third round

"I'm definitely very happy right now," the 18-year-old told ATPTour.com. "Ben is not an easy player to beat. I think I've got a game that kind of suits me to playing him."

Shang, who ousted Shelton 6-4, 6-4 at the Atlanta Open last week, converted five of his nine break point chances on Tuesday and polished off the victory in one hour and 42 minutes.

"In the past two weeks, I've been returning really well," Shang said. "So I think that was the key today, to break a few service games from him."

The left-hander from Beijing posted his fourth victory in as many days including two qualifying victories and a first-round triumph over Emlio Gomez.

He had started his year by qualifying for the Australian Open and winning a first-round match but was then slowed by mononucleosis.

Once back on court he qualified for the French Open, but didn't make it out of the first round.

Now ranked a career-high 149th in the world, Shang next faces either second seeded Frances Tiafoe or Aslan Karatsev for a place in the quarter-finals of the 500-level event.

Elsewhere Tuesday, former world number four Kei Nishikori of Japan withdrew with a left knee injury before his scheduled first-round match against South Africa Lloyd Harris.

Nishikori, 33, returned to competition from a 20-month injury absence in June, winning a low-tier Challenger Tour title in Puerto Rico before reaching the quarter-finals last week in Atlanta in his first ATP tournament since 2021.

Nishikori said he had experienced knee pain in Atlanta and after testing the knee Tuesday decided that he was "not good enough to play."

"I'm very disappointed because I always play good here," he said.

"But this is what it is, and I've got to keep climbing because I just started playing again and I know my body is not 100% strong enough to play many matches ... big tournaments are coming up, so I (will try to) be ready for that," added Nishikori, who gained direct entry to next week's Toronto Masters main draw after three players withdrew on Tuesday.