Australian Open, Melbourne
Venue: Melbourne Park Dates: 17-30 January
Coverage: Watch on BBC TV, Red Button, BBC Sport website (UK only) & Eurosport; listen on BBC 5 live sports extra and online; text commentary online;
It was a patchy show from Federer but he still had enough in his armoury
Roger Federer and Novak Djokovic produced contrasting displays as both secured their spots in the Australian Open quarter-finals in Melbourne.
Federer, world number two and defending champion, was given a scare by Tommy Robredo before stumbling through 6-3 3-6 6-3 6-2 after 40 unforced errors.
Third seed Djokovic had an easier day with a crushing 6-3 6-4 6-0 triumph over Spaniard Nicolas Almagro.
Djokovic will play Tomas Berdych who beat Fernando Verdasco 6-4 6-2 6-3.
Federer will next face Swiss compatriot Stanislas Wawrinka after he disposed of American Andy Roddick in straight sets.
Brilliant Wawrinka destroys Roddick
Wawrinka, 25, comfortably defeated the former Grand Slam winner 3-6 4-6 4-6 with a superb performance, playing excellent tennis, to set up a last-eight clash with Federer.
"I played an unbelievable match, I was ready for a big fight and I'm very happy with how I played tonight," said Wawrinka.
"I wanted to play aggressively, especially on my serve, and it worked. I am excited about the possibility of playing Roger. There was a great atmosphere in here tonight and I hope it will be the same on Tuesday."
In seven matches Wawrinka - who has known Federer since he was 16 - has only beaten his compatriot once.
"We know each other pretty well, so we'll see how it goes."
Earlier Federer survived a loss of form in a scrappy second set before finally coming through in four sets against Robredo, world number 52 and a quarter-finalist in this tournament four years ago.
"I was able to get off to a good start but it was always going to be tough," said Federer, who secured his 27th consecutive last-eight spot in a Grand Slam to equal Jimmy Connors' record.
I have the game to win a Grand Slam, I just have to believe in myself and be mentally strong
"Robredo makes you work. He moves extremely well and it was extremely hard. I'm sweating bullets and happy the match is over and really excited to be in the next round."
The last time the 29-year-old, eyeing a fifth title in Melbourne, failed to reach the quarter-finals in a Grand Slam was at the 2004 French Open, and all went to plan with a comfortable first set, starting in blistering style with three aces.
But with the 28-year-old Spaniard breaking to lead 5-3 in the second set, Federer looked stunned and as his uncharacteristic errors showed no sign of stopping, the match was soon level at one set all.
The Swiss admitted afterwards he had struggled with his return and lacked rhythm but despite facing a number of break points his back-hand and deft touch at the net remained his most potent weapons as he edged a nervy third set.
Still the mistakes continued, with several returns flying off his racquet frame, but Federer stayed calm in sweltering conditions to wrap up his 10th win in 10 matches against his opponent as a weary Robredo flicked a forehand well wide.
In complete contrast, it was a devastating performance by Djokovic who has now reached the last eight at 13 of his last 15 Grand Slam events.
With the 2008 champion losing at the quarter-final stage in the last two years at Melbourne Park, the Serb looked in determined mood and broke as early as the fourth game against Almagro to set him on the way to taking the opening set in 31 minutes.
Desperate to progress beyond the fourth round in this tournament for the first time, Almagro did his best but rarely threatened as he was decimated by an opponent dictating from the baseline and serving up 12 aces.
He was broken again in the fourth game of the second set and soon had to watch Djokovic dish up a pair of aces to open up a two-set advantage.
The demolition continued and after another break immediately at the start of the third set, the Serb raced away to secure his spot in the last eight.
"That was a higher standard than my previous matches and it's a big positive for me heading into the quarter-finals," said Djokovic who reached the quarter-finals in all four Grand Slams last year.
"I have the game to win a Grand Slam, I just have to believe in myself and be mentally strong."
The sixth-seeded Berdych, runner-up at Wimbledon last year, was another in cruise-control in a straight-sets triumph over Spaniard Verdasco, ranked nine, in a match that last just under two hours.
Verdasco racked up 39 unforced errors and struggled with his opponent's serve throughout - his receiving points won stood at just 17% - as the Czech booked his place in the quarters for the first time at the Australian Open.
In the first round of the Junior Boys singles, Britain's George Morgan and Kyle Edmund enjoyed mixed fortunes.
Morgan, ranked fourth, survived a first set tie-break to defeat Brazilian Thiago Moura Monteiro 7-6 (7-3) 6-4.
But Edmund was beaten 6-4 7-6 (7-2) by Mac Styslinger of the United States.