After restricting Paraguay to one shot at the half, coach Gustavo Alfaro injected Mauricio at the break and the Brazilian-born attacker fired an ineffective shot from distance five minutes after the restart.
The Paraguayans took the lead in the contest with the help of the energetic Julio Enciso, who repeatedly broke through the Australian defence.
He wasted one of Paraguay’s better chances with a low shot that went wide of the left post eight minutes from time.
In an end-to-end finish, Boas briefly got the Socceroos fans on the edge of their seats in the 89th minute when he split two defenders, charged into the box from the right and sent his shot wide of the far post.
Mauricio tested the middle late on when he found a bit of space on the edge of the area, but his slow, low shot was easily dealt with and Australia continued to press forward with more substance than style.