Champion Kim Clijsters, French Open winner Li Na, world No.1 Caroline Wozniacki and third seed Victoria Azarenka all advanced, along with local hope Bernard Tomic, dark horse Tomas Berdych and world No. 3 Roger Federer.
Mardy Fish became the first men's top-10 seed to exit Melbourne Park, though his 7-6, 6-3, 7-6 defeat by Falla left a bitter taste in the American's mouth, with the eighth seed suggesting much of Falla's treatment for cramping during a tense third set had been a tactical ploy.
"When you think someone is cramping or ailing physically, you sort of change your game a tiny bit," Fish said. "I think it had a significant bearing on the third set, for sure.
"Didn't seem like he was having too much trouble during the point. So it was a good tactic on his part." Controversy also boiled over on Margaret Court Arena when a David Nalbandian fumed at the chair umpire for over-ruling a point and denying him a Hawk-eye challenge toward the end of his four hour, 41 minute loss to American John Isner.
"I mean, it's ridiculous playing this kind of tournament with this kind of umpires. What is this?," Nalbandian railed after his 4-6, 6-3, 2-6, 7-6, 10-8 defeat.
"What did the ATP do for this? I didn't understand in that situation. I mean, can you be that stupid to do that in that moment?" Former Australian Open finalist Marcos Baghdatis also provided the Margaret Court crowd with fireworks when he smashed four racquets in a spectacular fit of pique after dropping serve early in the third set against Stanislas Wawrinka.
Nadal's knee, heavily taped after it had caused him "unbelievable pain" on Sunday, held up well under a test from Germany's Tommy Haas, the Spaniard coming through 6-4, 6-3, 6-4.
"A positive match, but not that ... demanding," Nadal said. "We didn't play four hours and a half, five hours.
"Three sets, so wasn't that tough." Federer, however, had a much easier day when he advanced without having to lace up his tennis shoes.
The Swiss had been scheduled to play Beck on Hisense Arena, ending a run of 52 matches at Melbourne Park on main show court Rod Laver Arena, before he found out his German opponent had withdrawn.
The 16-times grand slam champion, seeded to meet Nadal in the semi-finals, did not even have the chance to warm up.
"I was just coming for my warm-up hit, so I was completely focusing on the match, saying, 'Okay, I'll probably have two, three hours to go'," Federer told reporters.
"Now I'll just take it easy ... and come out tomorrow and hit intensely, and then I'll be ready for the next match." Women's top seed Wozniacki fought off a second-set wobble to knock out Georgia's Anna Tatishvili 6-1, 7-6 and the Dane said she felt like she had let her opponent back into the match.
"I thought the first set I played pretty well. I stayed aggressive and made her run," she said.
"Second set, she went a bit more for her shots, and I stepped back a little bit and she punished me for that.
The Dane joined Clijsters and Li in the third round, last year's finalists rarely needing to get out of first gear in their matches on Rod Laver Arena.
Temperatures were much more comfortable after two days of fierce heat and Clijsters barely built up a sweat as she thrashed France's Stephanie Foretz Gacon 6-0, 6-1.
"I felt like in my first match I didn't really have that rhythm that I would have liked to have," Clijsters said.
"I was hitting the ball well, felt that I could keep her under pressure. I didn't really let her play her game. From the beginning till the end, I did what I had to do well." Li, was almost as efficient, giving Australian Olivia Rogowska little time to settle and running out a comfortable 6-2, 6-2 winner in 62 minutes.
Tenth seed Francesca Schiavone suffered a shock defeat, however, dumped out by fellow Italian Romina Oprandi 6-4, 6-3.
