Rotterdam - Sixth-seeded Frenchman Jo-Wilfried Tsonga was kept guessing by unheralded Greek Stefanos Tsitsipas before grinding out a 6-4, 7-6 (7/2) first round win at the Rotterdam World Tennis on Tuesday.
The 19-year-old wildcard entry came onto the court as a complete unknown to Tsonga, who played the Dutch final in 2011, losing to Swede Robin Soderling.
Tsonga, returning to the Ahoy stadium for the first time since 2014, led by a set and 5-3 in the second set against the 205th-ranked challenger but was unable to kill off the match.
Instead, the 31-year-old had to take it into a tiebreaker, eventually making it into the second round in 89 minutes with four breaks of serve.
"It was difficult as I did did not know him at all," said the number 14. "That is unusual on the tour, never seeing someone before at all.
"I didn't know where to play at the start or what to expect. The entire match went like this. He went for it sometimes, other times he stayed back and was waiting.
"He surprised me during the entire match."
In round two Tsonga faces Sydney champion Gilles Muller after the Luxembourg veteran beat Dutchman Tallon Griekspoor 6-3, 6-2 with 14 aces as the number 317 youngster made his ATP main draw debut.
Holder Martin Klizan of Slovakia began his title defence with a defeat of Fernando Verdasco 6-4, 0-6, 6-1 while last year's semi-finalist Philipp Kohlschreiber took out eighth seed Lucas Pouille of France 7-5, 6-2.
Frenchman Gilles Simon overcame compatriot Nicolas Mahut 3-6, 6-3, 6-4.