With her win on Wednesday, Venus is through to the third round in NY for the 17th time.
"You can take the superhero out of her costume, but you can never take away her superpowers", it captioned a picture of Serena wearing her catsuit.
Venus emerged a 6-2, 6-4 victor, something her sister admitted she barely remembers, but Serena also revealed she reckons their individual success helps them both reach higher levels.
"It's early in the tournament, so both of us are going to be looking forward to continuing to play better, " Venus said. "But whoever you're feeling like - me or Venus - it'll work".
Williams, 38, notched up her 775th career win by seeing off Italy's Camila Giorgi 6-4, 7-5 as temperatures again climbed towards a sweltering 35 degrees. "I played so many other sports, and I was just interested in a lot of other sports and different things", said the world number 74 who faces French Open runner-up Dominic Thiem for a place in the last 16.
The precociously-talented Serena Williams then throws a tennis ball in the air, and looks set to launch a serve.
"I think that part is really remarkable", Serena said. Obviously I wish I could have been playing a little bit better. The No. 31 seed Verdasco took down the world's former No. 1 in four sets, beating Murray, 7-5, 2-6, 6-4, 6-4, in the second round. "I think the umpire was probably overwhelmed by the situation".
"I think that sometimes we've gone too far". Nadal won 46 of 55 first-serve points and wore down Vasek Pospisil, 6-3, 6-4, 6-2, in Ashe Stadium.
Elsewhere, two-time major champion Garbine Muguruza couldn't stave off an upset, leting a lead slip away in a stunning loss to 202nd-ranked Czech qualifier Karolina Muchova 3-6, 6-4, 6-4.