James Duckworth's preparations for Wimbledon have been hit by a shock defeat. -AAP Image
German teen Justin Engel had never played a professional tennis match on grass but he showed he could be a force to reckon with at the Stuttgart Open when he overcame Australian James Duckworth, who sits 187 rungs above him in the rankings.
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Engel, ranked 281 in the world, arrived at the tournament having played only five matches on the ATP Tour, with the 17-year-old a regular on the Challenger Tour where he has played on clay and hardcourts.
After slowly coming to grips with the green surface, Engel forced a deciding set but found himself a break down and even needed treatment for dizziness before triumphing 4-6 6-4 7-6 (7-5).
When Duckworth's return on match point found the net, the Australian nearly smashed his racket but controlled himself while a relieved Engel sank to the grass in disbelief before throwing his cap into the air in delight.
"I'm really proud of myself, it was my first grass match," said Engel, who fired 32 winners past Duckworth.
"I know this match was tough and I'm pretty happy with this result. I can't wait to play the next round."
American 19-year-old Learner Tien also advanced from his first match on grass but only after his opponent Yoshihito Nishioka retired when Tien had levelled the match at one set apiece.
Arthur Rinderknech led a bevy of Frenchmen into the second round when he upset fifth seed Denis Shapovalov 6-4 2-6 6-0.
His compatriots Corentin Moutet and Quentin Halys beat a pair of Italians, Fabio Fognini and Lorenzo Sonego respectively.
