Sabalenka dished up 21 double faults and was reduced to serving underarm in the second and third sets in a desperate effort to get the ball into play.
Andreescu, the 2019 US Open champion, who missed the entire 2020 season with injury, has played little in 2021 and hadn't won a match since reaching the second round at Eastbourne in June.
Australian Open 2021: Dayana Yastremska pulls out of tournament after failed appeal against doping suspension
The decision means that Yastremska, who is ranked 29 in the world, would not be able to play in the Australian Open in Melbourne, which is due to start on 8 February.
A punishment would not be decided until after a full hearing. The ITF said Yastremska has a right to appeal, but has not yet done so.
Palermo Ladies Open: Petra Martic to face Anett Kontaveit, Fiona Ferro against local favourite Camila Giorgi in semi-finals
Martic beat qualifier Aliaksandra Sasnovich 7-6 (5), 7-6 (3) then Kontaveit defeated Italian teenager Elisabetta Cocciaretto 6-1, 4-6, 6-1.
Qatar Open: Garbine Muguruza sets up quarter-finals against Ash Barty; Karolina Pliskova loses to rising star Ons Jabeur
Former No 1 Garbiñe Muguruza beat Ukrainian teenager Dayana Yastremska 6-2, 6-4 Wednesday to reach the quarter-finals of the Qatar Open.
Australian Open champion Sofia Kenin says she is frustrated by her inability to rediscover the rhythm she had at Melbourne Park after crashing out of the Qatar Open
Dubai Tennis Championships: Kim Clijsters loses in straight sets against Garbine Muguruza on return to WTA Tour
Kim Clijsters' first WTA Tour match since 2012 ended with a 6-2, 7-6 (6) loss to Garbine Muguruza at the Dubai Championships.
Australian Open 2020: Vintage Caroline Wozniacki comes back from the brink in second round win over Dayana Yastremska
Down 1-5 in first set, Wozniacki didn’t just start getting more balls back, she also started doing different things with the ball, forcing Yastremska to put a little more thought into her play.
Australian Open 2020: Serena Williams secures berth in third round; Coco Gauff to meet Naomi Osaka after three-set win
Checkout all the match results of the Women's Singles fixtures from the third day of the Australian Open 2020
Australian Open 2020: Ash Barty says it is amazing to get so much love from crowd, well-prepared for tournament
The world number one cannot have had much time to check out the city on Sunday having hot-footed it from South Australia, where she beat Dayana Yastremska on Saturday evening to win the Adelaide International.
Adelaide International: World No 1 Ashleigh Barty beats Dayana Yastremska in straight sets to clinch first title on home soil
Barty conceded just two points on serve during the first set, breaking the 19-year-old Yastremska's serve in the third and seventh games
Adelaide International: World No 1 Ash Barty beats Danielle Collins in three sets, to face Dayana Yastremska in final
Barty will meet World No 24 Dayana Yastremska in Saturday's final after the 19-year-old Ukrainian beat Aryna Sabalenka 6-4, 7-6 (4)
Adelaide International: Former Australian Open-winner Angelique Kerber retires from match with lower back injury
Kerber, who won the Australian Open in 2016 and also has Wimbledon and US Open titles, had on-court medical help for the injury and then retired
Kiki Bertens became the first player to qualify for the semi-finals of the WTA Elite Trophy in Zhuhai, China. The tournament is the second-tier year-end competition on WTA Tour.
Wuhan Open 2019: Ash Barty survives late scare to enter quarters; Karolina Pliskova knocked out by unseeded Dayana Yastremska
World number one Ash Barty fended off a late comeback attempt by American Sofia Kenin to reach the Wuhan Open quarter-finals on Wednesday, while second seed Karolina Pliskova was knocked out in straight sets by Ukrainian teenager Dayana Yastremska.
Pan Pacific Open 2019: Anastasia Pavlyuchenkova through to second round, Elise Mertens beats Whitney Osuigwe
Pavlyuchenkova, who lost the 2017 final to Caroline Wozniacki, went on a roll early in the second set to win 11 of the first 12 points and took a 4-0 lead before dropping serve
US Open 2019: Defensively solid Elina Svitolina pulls out all the stops to weather tough-battling Venus Williams
Facing pressure points — down 0-3 in the second set, and an impressive fight from the experience of Venus Williams, it was Svitolina who simply waited for Williams to falter
Dubai Tennis Championships: Daria Kasatkina downs qualifier Magdalena Frech in first round; Garbine Muguruza advances
Russia’s Daria Kasatkina roared back from a break down in the deciding set to beat Polish qualifier Magdalena Frech 6-3 3-6 6-4 in the opening round of the Dubai Duty Free Tennis Championships on Sunday.
Thailand Open 2019: 18-year-old Dayana Yastremska announces her arrival on big stage with impressive title win
While Dayana Yastremska seems to have all the ingredients to join the ranks of the Next Gen stars, she has a long way to go before she gets there.