Serena's emotional message to Wozniacki

Johannesburg - Caroline Wozniacki defeated Simona Halep in the Australian Open final on Saturday to lift her first ever Grand Slam trophy. 

The Dane burst in tears and collapsed to the ground as soon as she won, and she also become the new No 1 in women's tennis. 

As it turns out, the 27-year-old was not the only one to become emotional after her victory. 

Serena Williams, who won last year's title while she was pregnant with her first child, took to Twitter to congratulate Wozniacki on her title win and becoming the best in the world once more. 

Williams said that she had been "too nervous" to watch the match but that after she heard the news of Wozniacki's victory, she couldn't get back to sleep. 

"Too proud my friend," Williams added. 

Now 36, Williams has won 23 Grand Slam titles of her own. 

I got too nervous to watch but woke up to @CaroWozniacki new number one and aussie open champ. So awesome. So happy. Are those tears? Yup they are. ?? from a year ago to today I'm so proud my friend so proud. Literally can't even sleep now

— Serena Williams (@serenawilliams) January 27, 2018