At the 2016 Rogers Cup, when Andreescu was still a junior, the Canadian of Romanian descent met Halep, already an established name, and asked her for advice.
Andreescu subsequently turned professional but has not had the opportunity to take on her idol on the WTA Tour ahead of the Finals in Shenzhen, where they have been drawn together and will face off on Monday.
Romanian Halep has been impressed by Andreescu's progression and now, tasked with playing one of the tour's outstanding performers of 2019, she hopes to measure up.
"It's amazing what [Andreescu] has done," Halep said. "To win a grand slam at 19, play few tournaments and win them, it's a great, great job.
"I just want to tell her that she deserved it because she played really well these tournaments.
"I'm excited also to face her. It's going to be a big challenge for me because this year was up and down a lot. I just have a very big up during the Wimbledon [winning her second major], and the rest was not that great.
"I'm not thinking about winning or losing here. I just want to be able to play the matches."
Andreescu, the youngest player at the Finals, is one of three debutants, alongside Australia's Ashleigh Barty, the world No.1, and Belinda Bencic.
Petra Kvitova, the oldest player in the draw, sees this as part of the changing face of women's tennis, and she expects each of the three women new to the event to regularly visit the end-of-year showpiece.
"I just realised that I'm the oldest one of them, which feels pretty weird," Kvitova, 29, said. "But I'm going to take it.
"I spoke with Simona, she's just one year younger, and we made some fun of it. There are people here for the first time, but not the last time probably.
"We are going to see them often, I think. Yeah, I mean the new faces are coming. It's normal that the generation is just changing."