Coming off a high-powered and high-profile first opponent in Ekaterina Makarova, Williams was even more aggressive against King, who spent most of 2015 off the court nursing an injured back. As celebrity superfans Beyoncé and Jay-Z looked on, Serena was particularly dominant on serve, striking 13 aces in the 64 minute match, and losing just six points behind her first serve.
Still, Serena told press she wasn't totally satisfied.
"I just think it should have been a different scoreline for me," she said in her post-match press conference. "I feel like I made a lot of errors.
"But, you know, there's nothing I can do about that now. What really matters is I got the win. Hopefully I'll just get better."
Breaking serve three times over the two sets, Serena didn't face a break point at all on Thursday night, ending the match with a +10 differential in winners to unforced errors (38-28).
"It's stable," she said with a laugh. "I just got to keep it like that. It's two matches in, and usually you want to be able to play seven matches. It's not even close to the halfway point.
"I definitely want to keep it as good as it can be."
Up next for the six-time US Open champion is Sweden's Johanna Larsson, a semifinalist at last week's Connecticut Open. Larsson dispatached Ana Ivanovic's conqueror Denisa Allertova, 6-3, 6-1, to set up the the third round encounter.
A win over Larsson would gaurantee Serena passes Martina Navratilova's record of 306 Grand Slam wins; she tied the record on Thursday.
"I knew it was on the horizon. I knew at Wimbledon that I wanted to get there. Obviously I'm excited about that. But I would like to take one more step, several more steps."