World number one Rafa Nadal progressed to the third round of the Australian Open but conceded he could have been more clinical in a straight sets victory over Argentina's Federico Delbonis.
The Spaniard, bidding for a record-equalling 20th Grand Slam title, but first in Australia since 2009, converted just three of his 20 break point opportunities in a 6-3 7-6(4) 6-1 victory.
"I think I can do lot of things better. But it's not because of Delbonis. I can do things better because of myself. I need to play better," Nadal said.
There were difficult five-set wins for Dominic Thiem and Karen Khachanov and former champion Stan Wawrinka, before home favourite Nick Kyrgios entertained the crowd in a packed Melbourne Arena.
Kyrgios overcame Frenchman Gilles Simon 6-2 6-4 4-6 7-5 in a match where both players mimicked Nadal's service routine after they were handed time violations.
Karolina Pliskova, Belinda Bencic and Elina Svitolina recorded comfortable wins as all of the top 10 seeded players in the women's draw advanced to the third round in Melbourne for the first time since 2007.
Fifth seed Elina Svitolina racked up 31 winners on her way to a comfortable 6-2 7-6(6) win over American Lauren Davis.
Czech second seed Karolina Pliskova made short work of Germany's Laura Siegemund, firing eight aces and 22 winners to seal a 6-3 6-3 victory.
Romania's Simona Halep, the 2018 runner-up, endured a nervy time against British qualifier Harriet Dart before sealing a 6-2 6-4 win for the 90th Grand Slam main draw victory of her career.
German seventh seed Alexander Zverev moved into the third round for the fourth straight year with a 7-6(5) 6-4 7-5 victory over Egor Gerasimov.
Fifth seed Dominic Thiem of Austria recovered from a mid-match blip to overcome Australian wildcard Alex Bolt 6-2 5-7 6-7(5) 6-1 6-2.