Novak Djokovic defeated Benjamin Becker in straight sets, but had to see out a tough first set, where the Serbian needed to win a tie-break.
Williams had no such troubles as she defeated Kazakhstan’s Yaroslava Shvedova 6-3 6-1. She will go on to face Sloane Stephens in the last 16 who defeated fellow American Jamie Hampton.
Stephens’ relationship with Williams has been frosty of late, especially since Williams defeat against the 20-year-old earlier in the year.
"I think that's all old news now and we've moved on,"
Stephens said. "We are competitors, we are co-workers so it is definitely tough, but I think now we are in a good place."
Defending champion Andy Murray will face German Florian Mayer in the third round after he beat Leonardo Mayer 7-5 6-1 3-6 6-1.
The Brit was made to work harder than he would’ve liked by the hard-hitting Argentine, as Murray dropped his first set of the tournament.
The US Open has been kind to the over-thirties with the likes of Lleyton Hewitt, Tommy Haas and Na Li all winning yesterday.
2001 US Open winner Lleyton Hewitt defeated number 6 seed Juan Martin Del Potro in five sets. Speaking after the match, the 32-year-old Australian said, "I don't know how many years I have left to play and I was hankering to get out on this court again and put on a show."
The American crowd certainly enjoyed the four-hour spectacle, which ended
6-4 5-7 3-6 7-6 6-1.
35-year-old Tommy Haas beat Lu Yen-Hsun in straight sets in a continuation of his return to form. Speaking about training, Haas said:
"It's always about being smart, about how you train and what you do off the court. If your body allows you to do all that stuff, then it's really up to you in many ways."
Number 5 seed Na Li beat Brit Laura Robson 6-2 7-5. The two players met at this stage in last year’s US Open where it was Robson who has the upper hand.
Wimbledon runner-up Sabine Lisicki lost in straight sets to Russian Ekaterina Makarova, while Tomas Berdych beat American Denis Kudla in a close match.
All of yesterday's results can be seen
here.