Schnyder, the oldest ever player to make the main draw of a Grand Slam via qualifying, was outgunned by the five-time major champion in the first set and for the majority of the second.
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However, she bravely battled back from 1-5 down to 6-6, showing the sort of ability and court-craft which won her 11 titles and once took her to seven in the world rankings.
She even saved three match points in the tiebreaker before Sharapova’s 23rd winner of the night sealed victory shortly before midnight.
“My average match against her is like two hours and 20 minutes so I knew I was in for a battle no matter what my story is or hers,” said Sharapova who is now 21-0 in US Open night sessions.
“I knew we’d go out and relive the battles against each other.
“I know what a competitor she is and to come back on the tour is very admirable.”
Left-hander Schnyder made her US Open bow in 1997 — the year of the deaths of Princess Diana in Paris and Mother Teresa in Kolkata.
It was the year that Mike Tyson infamously nibbled on Evander Holyfield’s ear while Twitter was still nine years away.
Schnyder made the quarter-finals in New York in 1998 and 2008 before retiring in 2011.
Tuesday’s match was her first main draw appearance at the US Open since 2010 and her first against Sharapova in a decade.
“It doesn’t really feel that special,” said Schnyder. “It doesn’t feel like I have been gone for a while as tennis is a passion of my life.”
“Times passes really quickly and it doesn’t seem it’s eight years since I last played Maria.”
Schnyder was watched on Tuesday by three-year-old daughter Kim.
“She enjoyed it. She saw herself up on the big screen,” added Schnyder who does not know if her return to the tour will be permanent.
Her focus, she said, will be on her daughter.
“It’s more fun for me to get to know her world rather than her having to get to know my world of tennis.”
Understandably there were a few nerves on both sides on Tuesday.
Sharapova, the 2006 US Open champion, served up three double faults in the first game with the opening four games of the contest all breaks of serve.
The Russian 22nd seed steadied the ship with two more breaks, pocketing the first set with Schnyder losing all four of her service games and failing to hit a single winner.
Schnyder finally held serve for 1-1 in the second set before retrieving the breaks to get to 5-5.
“She still has incredible hands and moves incredibly well for being out of he game for so long,” added Sharapova.
“It took me like 15 years to drop shot Patty Schnyder and win a point.”
Sharapova will face Romania’s Sorana Cirstea for a place in the last 32.