Debutante keeper Andrea Beckenstein also played her part, saving well from an Owusu-Ansah header and then parrying a close-range effort from Blessing Agbomadzi, with Gifty Acheampong unable to convert the rebound.
Ghana remained on top and continued to dominate the Paraguayans physically, but the second half initially brought only more frustration in front of goal. Twice, they were clean through but on both occasions - first through Rafia Kulchirie, then Owusu-Ansah - they failed to find the target.
The Ghanaian captain would not be denied, though, and with 22 minutes remaining, she conjured up a spectacular clincher. Acheampong cushioned the ball into her path 25 yards from goal and Owusu-Ansah took it first time on the volley, sending a right-foot shot looping into the top right-hand corner.
Live Your Goals Player of the Match: Sandra Owusu-Ansah (GHA)