Australian Open 2015 Day 4 Results: Serena and Djokovic Breeze Through along with Wawrinka, Radwanska and Venus

Serena Williams and Novak Djokovic showed just why they are the players to beat at this Australian Open with comprehensive victories in their second round matches on Thursday.

Djokovic was ruthless and professional in his 6-0, 6-1, 6-4 smashing of Andrey Kuznetsov of Russia at the Rod Laver Arena, giving all his rivals a slice of the form that he is in as he looks for yet another Australian Open title.

The current defending champion in the men's singles – Stanislas Wawrinka -- did not have it as easy, with Romanian Marius Copil giving the Swiss a hard time in the first two sets, which Wawrinka won via tie-breakers.

Copil lost a bit of that steam in the third set, after going down 7-4 in both the tie-breakers, with the experience of Wawrinka coming to the fore in a 7-6, 7-6, 6-3 win, which now sets up a third round clash with Jarko Nieminen.

US Open finalist Kei Nishikori came from a set down to stop Ivan Dodig 4-6, 7-5, 6-2, 7-6 (0), while John Isner had to fight his way past Andreas Haider-Maurer6-4, 7-6 (4), 4-6, 6-4.

In the women's singles, Serena, playing just before Djokovic on the same court, survived a tough first set against the experienced Vera Zvonareva, before blowing the Russian away in the second to march into the third round courtesy a 7-5, 6-0 victory.

Joining Serena, who will now take on No.26 seed Eilina Svitolina, in the next round of the Australian Open in Melbourne is her elder sister Venus, seeded 18, after the experienced American dispatched compatriot Lauren Davis in straight sets 6-2, 6-3.

"Always good to advance," said Venus, who will face Italian Camila Giorgi in the third round. "That's pretty much the goal when you step on the courts, it's like, Come on. Let's get to the next round. Met the goal today."

Pole Agnieszka Radwanska also had an easy path into the third round, thumping Johanna Larsson 6-0, 6-1. Radwanska will next face 30th seed Varvara Lepchenko.

"I think it was great match," said the diminutive Pole. "I really start well. I played aggressive from the beginning to the end.

"And well, short, good match. So, you know, it's better, especially that it's really hot today. Be fresh for the next one."

In Indian action, Mahesh Bhupathi's return in the Grand Slams did not go so well as the veteran and his Austrian doubles partner Jurgen Melzer were beaten by Argentine duo Diego Schwartzman and Horacio Zeballos 6-4, 6-3.

Results (Round 2): Men's singles: Vasek Pospisil (Canada) beat Paolo Lorenzi (Italy) 6-7 (3), 7-6 (4), 6-3, 6-4; 1-Novak Djokovic (Serbia) beat Andrey Kuznetsov (Russia) 6-0, 6-1, 6-4; 4-Stanislas Wawrinka (Switzerland) beat Marius Copil (Romania) 7-6 (4), 7-6 (4), 6-3; 5-Kei Nishikori (Japan) beat Ivan Dodig (Croatia) 4-6, 7-5, 6-2, 7-6 (0); 12-Feliciano Lopez (Spain) beat Adrian Mannarino (France) 4-6 4-6 7-6 (3), 4-0 (Mannarino retired); 19-John Isner (U.S.) beat Andreas Haider-Maurer (Austria) 6-4, 7-6 (4), 4-6, 6-4; Jarkko Nieminen (Finland) beat Matthias Bachinger (Germany) 7-6 (4), 7-5, 7-5; Steve Johnson (U.S.) beat 30-Santiago Giraldo (Colombia) 6-3, 6-4, 6-2; Guillermo Garcia-Lopez (Spain) beat Alejandro Gonzalez (Colombia) 6-1, 6-3, 6-3.

Women's singles: 26-Elina Svitolina (Ukraine) beat Nicole Gibbs (U.S.) 7-6 (3), 7-6 (6); 11-Dominika Cibulkova (Slovakia) beat Tsvetana Pironkova (Bulgaria) 6-2, 6-0; 30-Varvara Lepchenko (U.S.) beat Ajla Tomljanovic (Croatia) 6-1, 7-6 (1); Camila Giorgi (Italy) beat Tereza Smitkova (Czech Republic) 6-1, 6-4; 1-Serena Williams (U.S.) beat Vera Zvonareva (Russia) 7-5, 6-0; Timea Bacsinszky (Switzerland) beat Anna Tatishvili (U.S.) 6-7 (5), 6-3, 6-2; 24-Garbine Muguruza Blanco (Spain) beat Daniela Hantuchova (Slovakia) 6-1, 1-6, 6-0; 18-Venus Williams (U.S.) beat Lauren Davis (U.S.) 6-2, 6-3; 6-Agnieszka Radwanska (Poland) beat Johanna Larsson (Sweden) 6-0, 6-1.