Venus Williams went to thank one person last night. But they weren't there.

It was a bittersweet moment when on Saturday night, Serena Williams beat sister Venus to take out the 2017 Australian Open.

The younger sister defeated her opponent 6-4 6-4 in a gripping game of tennis – one that had the audience asking very predictable questions.

Who does their mum go for?

How do they decide who sits in each box?

Were they having Christmas lunch together a few weeks ago? Isn’t it…awkward?

But it was a comment in Venus’ incredibly gracious speech that really cemented how intense the experience must be for the Williams’ family.

The 36-year-old spoke to the crowd at Rod Laver Arena, thanking her sister Serena and expressing her gratitude to even be “breathing.”

But when she went to thank her other sister, Isha, things didn't go as planned. Because when she looked for her in the audience, she was no where to be found.

"Sister Isha, where are you?" Venus asked as she looked for her in the crowd.

"She didn’t come?"

It was only a moment before Venus started to laugh and said, "I get it. It is too hard. I get it. Isha, I love you."

According to commentator Renee Stubbs, Isha had a good reason for not being at the stadium.

"Isha went back to the hotel and she watched it on television," Stubbs explained. "She didn’t want to be around it. She said as soon as it was over she was going to be back here."