MONTERREY, Mexico - Former Top 30 star Anna Karolina Schmiedlova shocked five-time Wimbledon champion Venus Williams to reach the second round of the Abierto GNP Seguros, scoring her first win since Wimbledon, 4-6, 6-3, 6-2.

"It's one of the best wins of my life," she said during the subsequent on-court interview. "I'm very happy it happened here in Monterrey.

"I came here from qualifying, just to be here to play someone as great as Venus Williams, so I'm very thankful. I haven't had an easy last year and beginning of this year, so I'm grateful for every win."

Williams was hoping to join sister Serena as one of two women to win matches across four decades, but it was Schmiedlova who kickstarted an injury comeback after six months away from the game, rallying from a set down to advance in two hours and 29 minutes on Estadio GNP Seguros.

The former World No.1 played Schmiedlova twice in 2014, splitting the two meetings with the latter winning their most recent encounter at that year's Roland Garros. Schmiedlova has been ranked as high as World No.26 but has seen her ranking swing up and down in recent years, falling back to the outer reaches of the Top 200 after a knee injury ended her season after Wimbledon.

Williams has endured her own struggles that began at the end of last season and continued into the new decade, losing in her first two tournament appearances to teenagers Cori "Coco" Gauff at the Australian Open and Kaja Juvan at the Abierto Mexicano Telcel just last week in Acapulco.

Showing little rust to start, the American shrugged off a break point in the opening game to surge ahead 5-1, employing deft angles and effortless power along the way.

"I started with a lot of respect, which is something you can expect when you're playing someone as good as Venus. I needed to get a little more confident and calm. Then, I started to play better at the end of the first set."

Schmiedlova, who came through qualifying with two straightforward wins over Lizette Cabrera and Varvara Flink, began to warm up at the 11th hour to narrow Williams' lead to 5-4 - saving three set points on the seven-time major champion's serve.

Williams rebounded to break for the set in the very next game, but Schmiedlova was in the match, twice leading by a break and navigating a dramatic eighth game, one that forced her to save two break points after leading 40-0, of a deciding set.

Another titanic game followed as Venus saw five game points go begging, allowing Schmiedlova to convert her second set point and level the match.

The Slovak carried that momentum into the final set, holding at love to move ahead 3-0 and saw a double fault from Williams help earn her a second break in the very next game. 

Williams put on a brave last stand, getting on the board and narrowing the lead to just one break behind some vintage aggression, but Schmiedlova wouldn't be denied, chasing down a backhand return from her more experienced opponent and smacking a cross court forehand winner for a 5-2 lead.

Earning a match point as Williams pushed a backhand long, she secured victory with one last forehand winner that seared up the line to hand the 39-year-old a fifth straight defeat - a streak that dates back to last fall at the China Open.

Awaiting the 25-year-old in the second round is No.9 seed Marie Bouzkova, who eased past Schmiedlova's compatriot Kristina Kucova in straight sets earlier in the day.

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