Two seeded players were eliminated as Veronika Kudermetova beat No. 10 Anett Kontaveit 7-5, 6-1 and American Bernarda Pera won a marathon first-set tiebreaker on her way to ousting Donna Vekic 7-6 (10), 2-6, 6-4.
"The first match after a long stop is never easy", Kasatkina said.
"It was the first match, obviously a bit of nerves, I had to find my groove", Kenin said afterwards. The 88th-ranked Fernandez was good on just two of her six break-point chances.
Kenin will play 13th seed Yulia Putintseva in the third round.
A red-hot Aryna Sabalenka opened 2021 the way she ended 2020: with a win.
World Health Organization chief scientist raises concern over South African variant
As of midnight, Friday, January 8, the HPSC has been notified of 4,842 confirmed cases of COVID-19 in Ireland. It brings the cumulative number of known cases in Ireland to 140,727 and the country's death toll to 2,336.
"There's no doubt this will be an historic week of tennis, and is the biggest-ever Australian Open lead-in week we have seen", Tennis Australia major events head Cameron Pearson said.
"Flipkens broke Kenin" s serve five times in the first set, including breaking the American to love in consecutive service games to take the first set after Kenin had served for the set with a 5-4 lead. The Spaniard saved a break point in the third game with a backhand victor down the line, eventually getting on the scoreboard with powerful play. The Spaniard's streak continued as she used a winning forehand down the line to earn another break point at 3-2, and she obtained the conversion for 4-2 after Mladenovic misfired on the volley. No. 7 seed Elise Mertens from Belgium withdrew with a right shoulder injury before taking the court; No. 8 seed Marketa Vondrousova of the Czech Republic fell to Hsieh Su-Wei of Taiwan, 3-6; 6-3, 7-6 (3); and No. 11 seed Jennifer Brady of the United States was ousted 0-6, 6-3, 6-4 by No. 87 Tamara Zidansek of Slovenia.
Heather Watson was forced to dig deep as she edged past young British rival Jodie Burrage at the Abu Dhabi WTA Women's Tennis Open on Thursday.
Burrage, 21, was playing a tour-level match for the first time after losing in the final round of qualifying and being given a lucky loser spot.
Last month, the opening Grand Slam of the season was pushed back three weeks and settled for February 8 in order to accommodate restrictions on worldwide arrivals to the state of Victoria.