(CNN) - Meghan, Duchess of Sussex, was in the crowd at Wimbledon on Thursday to watch Serena Williams in her second-round match against Kaja Juvan.
The American was shocked in the first set by the 18-year-old Slovenian but rallied back to take the match 2-6 6-2 6-4.
Meghan Markle appeared to be wearing a necklace adorned with an "A," the first initial of her son Archie's name.
It comes ahead of Archie Harrison Mountbatten-Windsor's christening, which will take place in the Private Chapel at Windsor Castle on Saturday, exactly two months after he was born on May 6.
Williams and the duchess are close friends, having met a few years ago at a charity event. Williams and her husband, Reddit co-founder Alexis Ohanian, attended the former US actor's wedding to Prince Harry last May.
Williams also co-hosted a lavish baby shower for Meghan in New York City earlier this year.
The 37-year-old Williams is bidding to win an eighth Wimbledon title but first since 2016 after taking time off to have a baby. She needs one more grand slam victory to equal Margaret Court's all-time record of 24.
But Juvan reminded her in the first set that it's unlikely to be a simple coronation.
"I just have to remember that I'm best at closing matches, I'm good at it," she told reporters. "it's just experience and match play. In the past two years I haven't played a lot of matches. I'm just trying to kind of get that back."
Williams will play mixed doubles Friday with two-time Wimbledon champion Andy Murray -- back at Wimbledon for the first time since 2017 after hip surgery -- and is looking forward to feeling the crowd fully behind her.
"Actually I'm curious, too," she said. "I'm going to be so happy when I go out there, it's going to be really cool."
She added: "Andy is a great player, like I said. I think he is mentally one of the toughest players out there."
Earlier Thursday, defending champion Angelique Kerber crashed out of Wimbledon with a shock second-round defeat to American Lauren Davis.
The three-time grand slam champion lost 6-2 2-6 1-6 to the 95th-ranked Davis.
Kerber took the opening set in just 31 minutes and looked set to cruise to victory but the diminutive Davis, standing at just 5 feet 2 inches, stunned the German who took just three games from the last two sets.
"I was trying to finding my game the whole match actually," Kerber told reporters. "I was not really feeling good from the beginning. I don't know why. I mean, the energy was not there.
"Of course I'm disappointed. It's not the way I would like to finish here or to play here. But you have sometimes days like that. You have to accept it. You have to learn from it, trying to forgot this as soon as possible."
However, it was a very happy Fourth of July for the American, who only made it into the Wimbledon main draw as a lucky loser after suffering defeat in qualifying over the weekend.
The 25-year-old Davis will now play Spain's Carla Suárez Navarro Saturday.
CNN's Sarah Dean contributed to this report.
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