Williams, a seven-time Australian Open singles winner, had lost earlier than the fourth round just once in her last 17 majors. She was seeded eighth in this year's tournament.
Per ESPN Stats & Info, Williams has now lost just five singles matches in the first week of hard-court majors:
Unforced errors proved to be the difference, with Williams committing 56 to Wang's 20. Wang also saved five of six break points to Williams' nine of 12.
Williams and No. 27 Wang were tied at four in the first set with neither woman earning a break. This Wang backhand winner, which earned a clap from Williams, was the best shot in the early going.
However, Wang went up a break in the ninth game. She then held serve to close out the set 6-4.
Unforced errors and missed break-point chances proved to be the difference.
Williams committed 18 unforced errors to Wang's five in the first set. She also went 0-of-4 in break-point opportunities, with three occurring while up 3-2. Wang eventually won the 14-point game to tie the set at three apiece.
Williams also had two double faults and won 61 percent of her first-serve points compared to Wang's 73 percent.
The second set started with both players holding serve through four games before Wang took a 3-2 lead after converting her second break point. This excellent forehand winner helped her get there:
Williams had a chance to earn a break down 4-3 but could not convert.
However, a tremendous effort with Wang serving for the match up 5-4 ended with Williams winning a 24-shot rally and earning her first break of the day.
The two eventually went to a tiebreak, where Williams dominated to secure the second set:
Wang and Williams both held serve for much of the third set, which was evenly matched for the most part. Williams held off break point twice serving down 1-0 and 4-3.
However, it was Wang who emerged the winner in the end with Williams serving.
Up 6-5, Wang had two match points, but Williams fought back to force deuce. However, Wang won the final two points, with the last one occurring after Williams hit a return into the net.
Williams and Wang had faced off once before, with Williams winning 6-1, 6-0 in the U.S. Open quarterfinals. This match was a stark contrast from the one in Queens, New York, as Ben Rothenberg of the New York Times tweeted:
This win is undoubtedly the biggest of Wang's career, but the confident and laser-focused 29th-ranked player in the world isn't celebrating mid-tournament, per comments relayed by Tumaini Carayol of the Guardian:
Wang now advances to the fourth round, where she will face Ons Jabeur.