The start of the game quickly aroused concerns in the mind of the 36th racket in the world, since it was down 0-3 after only 10 minutes of play.
9th-seeded Rybakina continued her march although, up 4-1, she had to resort to a break to receive treatment on a thigh.
With her three aces and first serve scoring rate at 80% (16 of 20), she quickly closed the opening set after 38 minutes.
Leading 2-1 in the second, Andreescu in turn sought treatment from the physiotherapist to treat his right shoulder. It was apparently the same pain that had caused his retirement in the semi-finals in Thailand two weeks ago.
After the ten-minute break, it was a visibly cheered up Andreescu who broke her rival’s serve to widen the gap. But that was just the first of a series of four breaks and blockades that tied the players at 4-4.
With three aces more, but being significantly less productive on all of his first serves (62%), Rybakina was still slightly more effective than Andreescu (59%).
The 23-year-old Kazakh was the first to string together four winning games in the meeting and this allowed her to make the difference to conclude the match in 1h 33min.
In the next round, Rybakina will face Czech Marie Bouzkova, ranked 26th in the WTA and winning 6-1, 6-1 over American Sofia Kenin, 149th in the world.
Fernandez wins in doubles
Earlier in the morning, Leylah Annie Fernandez and her American doubles partner Bethany Mattek-Sands defeated Brazilian Luisa Stefani and Kazakh Anna Danilina 1-6, 6-3 and 11-9 in a first-round match.
Fernandez and Mattek-Sands will now meet Russia’s Aliaksandra Sasnovich and China’s Yifan Xu.
The latter eliminated Britons Harriet Dart and Eden Silva 4-6, 6-1 and 10-6.
The 20-year-old Lavallois got off to a good start in the singles tournament on Sunday, with a 6-4, 6-2 two-set victory over Austria’s Julia Grabher.
In the next round, Fernandez will cross swords with the Polish and world number one, Iga Swiatek.
