Australian teenager Thanasi Kokkinakis has been defeated in the second round of the Delray Beach Open, succumbing to Ivo Karlovic.
Karlovic, who turns 36 at the end of the month, defeated the 18-year-old 7-6 (7-4), 7-6 (7-2) this week.
The fourth-seeded Karlovic, a runner-up at Delray Beach in 2010, moved into the quarter-finals, where he will face seventh-seeded Steve Johnson or 17-year-old Russian Andrey Rublev.
Kokkinakis won his first ATP main draw match last week, beating Serbia’s Filip Krajinovic in the first round of the Open.