Umag - Croatia's Borna Coric beat Marcel Granollers 6-3, 6-3 in hot and humid conditions on Tuesday to reach the second round of the Croatia Open.
Seventh-seeded Coric felt at home with the weather, converting four out of 11 break points and scoring 35 winners to defeat his Spanish opponent.
"Conditions were very tough, but I like to play when it's like this, when the ball and court is slow, so I have more time," Coric said.
He next faces Britain's Aljaz Bedene.
Sixth-seeded Phillip Kohlschreiber of Germany also advanced after saving five break points to beat Santiago Giraldo of Colombia 6-3, 6-2.
Kohlschreiber started slowly and faced two break points before stepping up his game at 3-3 in the first set, and going on to win five games in a row.
Eighth-seeded Martin Klizan of Slovakia had to dig deep to defeat Pablo Carreno Busta of Spain 7-6 (7/3), 6-7 (8/10), 6-1.
Both players exchanged breaks in the middle of the first set before the Slovakian prevailed in the tie-breaker. Neither player was broken in the second set, with Carreno Busta winming the tie-breaker on his fourth set point.
Klizan made the stronger start to the final set, winning the four opening games before sealing victory.
In other first round matches, Bastian Trinker of Austria came from a set down to defeat Mikhail Youzhny of Russia 2-6, 6-3, 6-3 and Paolo Lorenzi also rallied to beat fellow Italian Matteo Trevisan 1-6, 6-2, 7-5.
Andreas Haider-Maurer, Damir Dzumhur and Joao Sousa also advanced to the second round.