Seeded 10th here, Williams ground her Japanese opponent into the red Parisian dust in a contest that at times almost veered into miss-match territory before ending 6-3 6-1.
Williams never appeared extended on the Philippe Chatrier court, but she nevertheless delivered a display of exquisite shot-making to a crowd denied a real contest.
Punching her black and lime-green racquet through the ball, Williams cleaned the lines with her groundstrokes, sending Nara scampering all round the arena.
"You know, it's always a joy when you can control the match," she smiled afterwards. "That always feels good."
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The win makes her the oldest woman to reach the third round at the French Open since Billie-Jean King in 1982, .
Next up is either Dutch qualifier Richel Hogenkamp or Belgian Elise Mertens.
"I don't think I have played either in singles, so it will be interesting to, like, see how that ball is coming at me," she mused.
"I just want to win, so whoever I play, I just would like to win that match. That's how you have to be is greedy."
It is Venus's 20th attempt at winning this title, and time may be running out for her, and for tennis fans to enjoy her languid shot-play.
She came closest in 2002 when she was beaten in the final by her younger sister, as she was at both Wimbledon and the U.S. Open that year.
There is no Serena standing in her way here, but plenty of younger guns are eager for a notable victory.
Serena for one, though, is in her corner.
"Yeah, she said, 'Good job'. She came in sometime during the match. I don't know exactly when.
"She knows exactly what it's like out there, and she's had a lot of success here. If she stays here through the end, I would like that."
(Editing by Hugh Lawson)
