Irate, the top seed sauntered to her changeover chair and hammered her racket repeatedly into the court before tossing it backward. The racket slid through the slick grass on Centre Court and landed in the lap of a cameraman positioned in the photo pit.
Williams missed a host of opportunities in the opening set, converting 1 of 9 break-point opportunities while donating 16 unforced errors. But after a difficult start, Williams beat McHale 6-7 (7), 6-2, 6-4 to reach the third round at Wimbledon.
"I was just really, really, really angry," Williams said after the match. "I had a lot of chances. She got really lucky on some shots. She just was playing great. I was a little disappointed in myself at that point."
Asked by ESPN for a statement on possible penalties that could result, the All England Club referenced the rule regarding racket abuse, which in part states, "Players shall not violently or with anger hit, kick or throw a racquet or other equipment within the precincts of the tournament site. Violation of this section shall subject a player to a fine up to $20,000 for each violation."
The rule also says that, after the match, the chair umpire will submit a report to the referee's office, which will review the incident and issue any penalties.
This was a comparatively mild outburst from Williams. Famously, she threatened to shove a ball down a line judge's throat at the 2009 US Open, an incident that cost her a point penalty and ultimately the semifinal match against Kim Clijsters. Williams was handed the maximum $10,500 on-site penalty at the time and subsequently issued a $175,000 fine by the Grand Slam committee and placed on a two-year probation.
Two years later, Williams again lost her cool at the US Open, this time in the final against Samantha Stosur, when Williams shouted in the middle of the point and the chair umpire awarded the point to Stosur under the "hindrance rule." Williams vehemently argued the decision and, still under probation, she was fined $2,000 but received no suspension.
Williams has endured a good amount of frustration this season. A year after winning three of four Grand Slams, she has fallen short in key moments, losing the final in both the Australian and French Opens. All told, Williams has only one title, in Rome, in 2016.
On Saturday, she will take on Germany's Annika Beck.
The match on No. 1 Court was delayed four times by rain, including once with Williams holding a match point at 7-6 in the third set. When play resumed, Kasatkina saved the match point and held to 7-7.
Four games later, the eighth-seeded Williams broke to end the contest, with Kasatkina slapping a forehand into the net on the final point.
The Associated Press contributed to this report.