Rafael Nadal & Roger Federer into Australian Open last 16

Rafael Nadal
Nadal finished with a first-serve percentage of 81%

Rafael Nadal showed glimpses of his very best form to make round four of the Australian Open with a crushing win against Slovak qualifier Lukas Lacko.

Nadal won 6-2 6-4 6-2 in an hour and 55 minutes and the world number two next plays 18th seed Feliciano Lopez.

Roger Federer was no less impressive in a hard-fought 7-6 (8-6) 7-5 6-3 victory over Ivo Karlovic and he will face Bernard Tomic.

Seventh seed Tomas Berdych beat Kevin Anderson 7-6 (7-5) 7-6 (7-1) 6-1.

Berdych will next play 10th seed Nicolas Almagro, who beat 21st seed Stanislas Wawrinka 7-6 (7-2) 6-2 6-4. Eleventh seed Juan Martin del Potro also plays on Friday.

Nadal has not been at the top of his game since the 2011 US Open, but he certainly was against 119th-ranked Lacko.

"The body is fine, I'm very happy to be in the fourth round," said the Spaniard, who was again playing with a heavily strapped right knee.

"It was a really complete, solid match and I'm very happy about my game. Being in round four without losing a set is fantastic."

Nadal opened the match with a break of serve to love, but the talented Lacko hit back immediately when Nadal netted a backhand.

However, the second seed reasserted his authority in game five and broke again for 5-2 before serving out to love.

He struck in game one of the second set, while breaks in games three and seven of the third proved decisive.

Nadal's delivery was particularly strong - he finished with a first-serve percentage of 81% - but his movement, defence and ball striking were also much improved.

In 57th-ranked Karlovic, Federer faced a tougher task and he needed two hours and 17 minutes to triumph.

The 16-time Grand Slam champion missed a pass to give his big-serving opponent a 6-5 lead in the first-set tie-break.

But he managed to lob the 6ft 10in Croat to level and expertly took the next two points to assume control of the match.

After saving a break point in game two of the second set Federer struck late to extend his advantage and a single break in the third allowed him to serve out the contest.

"I knew it would be tough," said the Swiss third seed. "I've played him 10 times on tour and knew it could come down to a few points here and there.

"I needed a bit of luck too, especially in the tie-break. I definitely got fortunate but I got better as [the] match went on."

Australian Tomic defeated Ukrainian Alexandr Dolgopolov 4-6, 7-6 (7-0), 7-6 (8-6), 2-6, 6-3.

Spain's Feliciano Lopez beat American John Isner 6-3 6-7 (3-7) 6-4 6-7 (0-7) 6-1, while Germany's Philipp Kohlschreiber beat Alejandro Falla of Colombia 6-3 6-2 7-6 (7-3).