The third seed won 7-6(7) 6-3 6-4 to progress to the third round.
The 22-year-old has been ruled out for three months with a partial stress fracture of the lumbar spine.
Ronaldo limped off towards the end of training on Tuesday after suffering a knock on a persistent left thigh problem.
Karlovic, seeded 27, banged down 41 aces in a 6-7(2) 6-3 7-6(3) 6-7(4) 12-10 victory against the 22-year-old wildcard.
PCB should have formed four teams and conducted matches among them, says former leg-spinner.
Navy takes their overall medals tally to 23-13-8 to lead the table.
Rafael Nadal remains the only teenaged champion in the past 25 years
Akhtar's red-hot fourth over stirred a batting collapse that saw Pakistan win by 67 runs.
- Chief selector Inzamam shortlists players for second phase of training
- Aisam, Nestor advance
- Murray survives fresh five-set Paris battle
- Compton promises no let-up from England
- Pakistan ‘A’ team named for England tour
- ‘Australia close to Gillespie swoop’
- Elshorbagy makes flying start in Dubai
- ‘Superman’ De Villiers steers Bangalore to IPL final
- Losing Stokes a big blow: Pietersen
- Kluge wins 17th stage, Kruijswijk stays in pink
- United hold day two of Mourinho talks
- Punjab Blues, KP Whites record big wins
- Pakistan 1 fall in semis as India set title clash with Iran 1
- KCCA trials for senior event from Saturday
- Women’s team to miss Asian netball
- Promise of land ends stadium dispute