Top-ranked Serena Williams fended off three set points before going on a 10-game roll to beat Vera Zvonareva, 7-5, 6-0, and move into the third round of the Australian Open.
The men's No. 1 seed, Novak Djokovic, had an easier run, spending a minute less than Williams on Rod Laver Arena in his 84-minute, 6-0, 6-1, 6-4 win over No. 88-ranked Andrey Kuznetsov on Thursday.
Defending champion Stan Wawrinka, who ended four-time champion Djokovic's 25-match winning streak at Melbourne Park in the quarterfinals last year, advanced to the third round for the seventh consecutive year with a 7-6 (4), 7-6 (4), 6-3 win over No. 194-ranked qualifier Marius Copil.
Williams, seeking a sixth Australian and 19th Grand Slam title, saved three set points in the ninth game before holding to swing the momentum of her match against Zvonareva, a two-time Grand Slam finalist who played only five tournaments in 2014.
Williams said Zvonareva started out really aggressively "and I was a little too passive."
That's when she told herself: " 'You know Serena, you've done so well here, you have nothing to lose' — and I started playing a little better."
After breaking Williams' serve twice in the first set, Zvonareva only won eight points in the second set and didn't get close to another break-point chance.
Venus Williams earned a 6-2, 6-3 win against fellow American Lauren Davis. The elder of the Williams sisters, a seven-time major winner, hasn't been beyond the third round at a major since reaching the fourth round at Wimbledon on 2011.
Sixth-seeded Agnieszka Radwanska needed only 44 minutes to race through her 6-0, 6-1 win over Johanna Larsson, continuing her run of reaching the third round or better at every Australian Open since 2010.
No. 24 Garbine Muguruza beat veteran Daniela Hantuchova, 6-1, 1-6, 6-0.
On the men's side, U.S. Open finalist Kei Nishikori beat Ivan Dodig, 4-6, 7-5, 6-2, 7-6 (0), getting a crucial service break in the 10th game of the fourth set when Dodig was serving for the set and then dominating in the tiebreaker.
No. 12 Feliciano Lopez was leading, 4-6, 4-6, 7-6 (3), 4-0, when Adrian Mannarino retired from their second-round match and No. 19 John Isner beat Andreas Haider-Maurer, 6-4, 7-6 (4), 4-6, 6-4.