"The first thing I did was close all my social media because I really get overwhelmed by that kind of stuff," said Andreescu, when asked about how she mentally prepared for the Williams challenge on Friday, after the intense high of toppling Wozniacki the night before.
"I still haven't touched my phone since [Thursday] night."
Andreescu still seemed slightly in disbelief as she faced the media just after midnight, following her 6-7 (1) 6-1 6-3 victory in two hours and 25 minutes.
"It feels like a double dream," said Andreescu. "I'm really just speechless, I don't know if this is a dream. [Could] one of you could pinch me please? Honestly, I've worked really hard for this moment and I'm really grateful."
After losing the first set tiebreak, the qualifier looked in trouble when she trailed early in the second set against Williams, before quickly swinging the momentum. Andreescu broke Williams, then reeled off eleven straight games, showing scant respect for one of the most feared serves in the sport.
"I was like 'what is going on?'", admitted Andreescu. "I just broke her five times in a row...she is one of the best servers in the game. She didn't serve as well as other matches I've seen her play but I took control of that. It was honestly a gift today. Maybe a late Christmas present. I tried to put pressure [with] the return."
There was one final twist in the match, when Williams embarked on a comeback from 0-5 down in the third set, threatening to steal the glory.
"I got really tight at 5-0," said Andreescu. "I thought…I'm one game away from winning this. But then she started raising her level and I stepped back. Then at 5-3 I thought 'screw this, I'm going to go for everything'. And that's what I did. And it worked. Maybe I should just that for every point."
It's hard to believe that Andreescu is sitting outside the WTA's top 150, given the form she has exhibited over the last two matches. She's been on tour for almost three years – and had some decent results in that time – but this is the undoubted highlight of her career so far.
"A lot has happened," said Andreescu. "I've worked really hard for this moment. There have been a lot of tough times. Seeing a lot of the younger players doing well gives me inspiration."
"You have to start somewhere. This is just my awakening moment. I'm just really happy and hopefully I can continue like this for the rest of my season, rest of my career."