Roger Federer might have ended his defense of his doubles Olympic gold after the Swiss master and his partner Stanislas Wawrinka crashed out in the doubles, but the 17-time Grand Slam champions is looking almost unstoppable in the singles.
In the latest match on his quest for singles Olympic gold, Federer scored a straight-set 7-5, 6-3 win over Uzbekistan's Denis Istomin, but later tasted defeat in the doubles to Israeli pair Jonathan Erlich and Andy Ram.
"I'm disappointed but overall I'm feeling good," Federer said. "Best-of-three-set tennis is very fast.
"There is no room for error really. In the doubles, even more so. I think we played two good doubles matches and I'm playing well in the singles."
Federer will take on John Isner in the quarters after the American defeated Serbian Janko Tipsarevic 7-5, 7-6 (16-14). Federer had to overcome a little hiccup in the opening set, before seeing out the match more comfortably in the second.
"It was tough," Federer said. "A very difficult first set, obviously there was a rain delay.
"It made it a little more nerve-racking as I was down in the score at 5-5, 15-30. I was happy with the way that I was able to turn it around. Denis, I thought, played a very good first set; I didn't play poorly to let him back into the match.
"In the second set I guess I learned from the first set and was able to bring it home, so I'm very happy."
Djokovic is seen as Federer's biggest threat to a gold medal and the Serbian was made to work very hard for his 4-6, 7-5, 6-1 win over Australian veteran Lleyton Hewitt. "I think he plays his best tennis on grass," Djokovic observed. "He's a former world number one. I have a lot of respect for him. He's a great competitor."
The Serbian former world number one will take on Jo-Wilfried Tsonga, in what promises to be an entertaining encounter.
Home hope Murray was also in a spot of bother against Marcos Baghdatis, but clawed his way back from a set down to score a 4-6, 6-1, 6-4 win, to the immense relief of a boisterous crowd.
"At the start of the match it was very windy and it pretty much continued that way," Murray said. "But, you know, after playing two matches indoors, where there's none of that to worry about, it did take me I was pretty unsure of myself at the beginning of the match, didn't feel comfortable on the court.
"Then, yeah, managed to settle myself down and move my feet better to get in better position in the second set. Played some good tennis after that. But it was very, very different conditions to the first two rounds."
Murray, who will play Spaniard Nicolas Almagro in the last-eight, praised the crowd for their support, but admitted the closer he is to a medal, the bigger the pressure. "When you play in front of a home crowd, the support is great. It can push you on when you're in tough situations.
"But with that, does also come a bit of extra pressure. And today there was a fair amount of tension on the court. That's probably why my celebration was what it was. It was a release of that tension."
