Novak Djokovic came through his first serious test of the Australian Open, as he was made to battle to claim a 6-4 6-3 7-5 win over Radek Stepanek.
The defending champion had been imperious in his wins over Paul-Henri Mathieu and Ryan Harrison but he showed he can also graft as well as cruise by beating the Czech.
That Djokovic's level was not as high as in the first two rounds owed much to the performance of Stepanek who has been emboldened since helping Czech Republic to Davis Cup glory last year. The Davis Cup success is unlikely to propel his career forward in the way it did for Djokovic, but at 34 he is showing there is life in his legs.
Stepanek matched Djokovic from the off, with his guile, changes of pace and serve-volley tactics offering a different puzzle for the defending champion to solve.
It looked like the Czech was all set to take a surprise lead as he worked break point in the seventh game of the opening set and was in control of the point, but a lucky net cord came to Djokovic's rescue.
Djokovic held to love to lead 5-4 and he put Stepanek under pressure with a brilliant passing shot. Stepanek netted a forehand to hand the No. 1 seed three set points. He persisted with his tried and trusted serving and volleying, but it let him down at the vital point as he dumped a volley into the net.
If Djokovic was hoping Stepanek would go away, he was out of luck as the second set followed a similar path to the first.
The Czech wowed the crowd in the sixth game with an amazing piece of play to retrieve a lob with a stunning backwards overhead. He chased the ball back in, forcing Djokovic to attempt a second lob. This time the ball landed long - prompting a jig of delight from Stepanek. It was not quite in the Si mould, but it could be classed as Stepanek-style.
Although his power and penetration were down on previous rounds, Djokovic kept probing and the break came in the eighth game. A low passing shot forced a short volley and he dashed up for the kill - which set him on the way to the second set.
Still Stepanek stood tall and he won an arduous opening service game of the third set that lasted 18 minutes.
Stepanek saved break points in the fifth game and again in the seventh, the second of which came courtesy of a quite exquisite half-volley that the great net players of the past would have been proud of. And he worked a break point of his own one game later, which Djokovic swatted away with an ace.
And typical of a champion, Djokovic stepped things up a level in the 11th game. Some stunning play worked three break points, the second of which he took when a tired Stepanek netted a backhand.
Djokovic has been imperious on serve in the tournament and he wrapped up victory - albeit after one last stand from Stepanek who won a magical point when again chasing down a lob and firing a passing shot.
The 10th seed Nicolas Almagro powered into the fourth round, proving too strong for Jerzy Janowicz in straight sets. His reward is a meeting Janko Tipsarevic who came through yet another five-set battle to beat Julien Benneteau.