The American world number one, playing for the first time since her third-round singles exit at Wimbledon, showed no sign of illness or rust as she rolled to victory over the 45th-ranked Czech in 64 minutes.
After enjoying a first-round bye, the top seed punched her ticket to the quarter-finals of the WTA hardcourt tournament where she'll face the winner of Thursday's second-round match between former world number one Ana Ivanovic and Canadian qualifier Carol Zhao.
Williams has captured titles at Brisbane, Miami and Rome in 2014, but she has failed to add to her tally of 17 Grand Slam singles titles and the US Open offers her last chance this year to do so.
After falling in the third round of singles play at Wimbledon, Williams looked wobbly in a second-round doubles match from which she and her sister Venus eventually retired.
Since then Serena had withdrawn from a tournament in Bastad but she said this week her time off had helped her recover from a virus and she showed no ill-effects on Wednesday.
"She had a really good serve," Williams said of Pliskova, who kept the first set close but finally surrendered the frame when Williams broke her in the final game.     

Williams broke again in the second game en route to a 3-0 lead in the second and broke Pliskova to love to close out the match when the Czech belted a forehand long.
Williams saved all three break points she faced in the match and fired nine aces.
"I think I played really well," Williams said.

"I'm on the right path. I'm excited and I'm looking forward to my next match,” she added.

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