In an inter-generational first-round encounter between wild cards at the Libéma Open, Celine Naef scored a memorable win on her WTA main-draw debut, coming from a set and a break down to defeat Venus Williams 3-6, 7-6(3), 6-2 in 2 hours and 18 minutes.

Williams, 42, is a former World No.1 who owns seven Grand Slam singles crowns, five of which have come on the grass of Wimbledon. Naef, 17, is a former junior No.4 who had never played a tour-level match before. The Swiss teenager was born on June 25, 2005 -- midway through the third of Venus' Wimbledon title runs. In a further wrinkle, Naef's childhood coach was Melanie Molitor, the mother of Venus' old rival Martina Hingis.

A hamstring injury sustained in Auckland at the start of the year had sidelined Venus since January. But she came out in imperious mode, knocking off a series of vintage volleys en route to taking the first set.

's-Hertogenbosch: Naef, 17, denies Venus Williams with comeback win

Watched by sister Serena, who retired from the sport last year, Venus maintained her momentum in the second set, pressuring Naef into error and breaking for 3-2. But Naef has enjoyed a superb transition to the pro tour so far, rising from No.904 last September to her current No.202. Her record this season now stands at 29-8, and she showed her quality as she fought back.

The climax of the second set was thrilling, with both players showing all-court skill with passes, drop shots and volleys. Venus' forehand was crucial in keeping her in the set -- until the tiebreak, when it let her down with three key unforced errors.

After a sequence of three breaks to begin the decider, Naef took control as Venus fell away. The American racked up 41 unforced errors, 16 of which came in the last eight games.

Serena Williams watching sister Venus in action at the Libéma Open.

Mathias Schulz/WTA

"I cannot believe I had the chance to play against Venus," said Naef afterwards. "She's an amazing player and really a role model for anyone.

"For me, it was the biggest stage I ever played. It was incredible and amazing to play in front of such a big crowd. I was very nervous, maybe you could see, but I tried to keep going and try my best."

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Naef will next face No.8 seed Caty McNally, who needed just 65 minutes to take out fellow American Katie Volynets 6-2, 6-1.

Elsewhere in first-round action, No.4 seed Ekaterina Alexandrova kicked off her title defence with a 6-3, 6-4 defeat of Evgeniya Rodina; and No.6 seed Bianca Andreescu survived a valiant effort from Turkish qualifier Zeynep Sonmez, advancing 6-4, 6-4. Sonmez, 21, was also making her WTA main-draw debut.