They conceded an early lead and had to battle a determined Croatian side hard through the second and third quarters.
But as the game moved into the final stanza they began to make some defensive stops and break away for easy baskets, finishing the game on a 30-9 run.
'I think you're going to see that a lot,' said USA point guard Sue Bird of the late surge.
'Our biggest advantage over most teams is our depth and our ability to just keep throwing people at you and wear you down.'
Tina Charles led the way with 14 points, while Angel McCoughtry added 13 and Candace Parker 11 with 13 rebounds.
Jelena Ivezic had 22 points for Croatia, with Marija Vrsaljko registering 19.