CNN  — 

There were mixed fortunes for the Williams sisters in the first round of the US Open on Tuesday.

As Serena, a six-time champion at Flushing Meadows, made history by winning her opening match against fellow American Kristie Ahn, her older sister Venus bowed out after defeat to Karolina Muchova.

Serena had suffered a number of surprise defeats in the build-up to the tournament and was tested against the 96th ranked Ahn, coming back from an early break in each set to win her 102nd game at the US Open, 7-5 6-4.

In the process, the 38-year-old surpassed Chris Evert as the all-time leader in matches won at the US Open.

“I don’t think I appreciate it enough, which is unfortunate,” Serena told reporters when asked about her record-breaking achievement.

“But I’m in the middle of a grand slam, so it’s not the time to be focused […] on records when I’m thinking about winning a tournament.”

READ: Andy Murray pulls off escape act in US Open win

Serena Williams sets a new record at the US Open with victory over Kristie Ahn.

Record major

The real prize for the 23-time grand slam champion remains winning another major which will see her tie with Margaret Court for the all-time record.

However, her home fans will not be present as Serena chases that 24th grand slam with games being played behind closed doors amid the pandemic.

“I think the hardest [thing] is making sure you stay pumped,” she told reporters after the game. “For me it was clearly easy because I’m always overly passionate. I love being passionate. It’s what I’m best at.”

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PERTH, AUSTRALIA - JANUARY 03: Serena Williams's husband Alexis Ohanian, holds their daughter Alexis Olympia Ohanian Jr. following the women's singles match between Serena Williams of the United States and Katie Boulter of Great Britain during day six of the 2019 Hopman Cup at RAC Arena on January 03, 2019 in Perth, Australia. (Photo by Paul Kane/Getty Images)
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03:52 - Source: CNN

Venus suffers rare defeat

Whilst Serena basked in yet more success, Venus fell to defeat.

The 40-year-old had never lost an opening match at the US Open before, having won her previous 21 first round ties.

However, world No. 20 Muchova proved too strong for the two-time US Open champion with the match ending 6-3 7-5 in favor of the Czech.

Despite the defeat, Venus remained positive about the sport she started playing professionally at just 14.

“I love this game,” she told reporters. “I’m good at what I do.”

“It’s easy to stay motivated and excited about doing something so amazing. Not many people get to do this.”

Serena will now face Russia’s Margarita Gasparyan in the second round on Thursday.