WATCH: Serena Williams cheers sister Venus on during American's Miami Open 1R match, reunites with ex-coach Patrick Mouratoglou

Serena Williams was spotted at the Miami Open, cheering for sister Venus Williams from the stands during the latter’s opening-round contest against Diana Shnaider.

While Venus Williams would go on to lose the contest 6-3, 6-3, fans were treated to some vintage shotmaking as well as the sight of both Williams sisters at the same venue for the first time in months.

Serena Williams was accompanied by her daughter Olympia. Moments capturing her support for Venus Williams from the sidelines have since made their way to social media, with the WTA’s official channel also sharing a short clip featuring the 23-time Grand Slam champion.

"That look at the end 😊 @serenawilliams is in the house 👋 #MiamiOpen," WTA caption the 'X' post.

Videos showing Serena Williams reuniting with her former coach Patrick Mouratoglou on the sidelines of the Miami Open were also widely shared on social media.

Both Venus and Serena Williams are former champions at the Miami Open. In fact, Venus, who was making an incredible 22nd appearance at the WTA 1000 event, tied her younger sister for most matches played at the tournament — 85.

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Venus Williams and sister Serena Williams' unmatched legacy at Miami Open

Venus Williams and Serena Williams have 11 Miami Open titles between them.

Venus and Serena Williams shared 11 Miami Open titles between them, with the former setting the ball rolling by lifting the trophy in 1998.

The 44-year-old would go on to win the title on two more occasions -- 1999 and 2001. Her younger sister, however, took things to the next level, triumphing at the Miami Open on eight occasions between 2002 and 2015.

While Serena Williams has hung up her tennis racket, Venus continues to slug it out on the court against opponents — Diana Shnaider included — who were not even born when she won her first Grand Slam.

Venus Williams’ former hitting partner David Witt shed some light on the American’s longevity in a recent interview with the WTA. He said a player is capable of staying out on the court for as long as their mentality allows provided they stay injury-free. Witt added that he believed in Venus Williams' ability to still play “unbelievable” tennis.

“I think when you’re out there and your brain is telling you one thing and your body’s telling you another thing, maybe injuries come into play and your body doesn’t recover as fast as it did when you were 25 or 30 or 35,” David Witt said.

“Even now, I think she’s capable of going out and playing unbelievable tennis,” he added.