"A few saves early and they're the important ones to keep your team in it and we got away with a one-nil win.
"If those saves weren't made we could have been down early and our confidence could have been knocked down.''
The Matildas scored the only goal against the run of play in the 41st minute, striker Michelle Heyman beating Ferns keeper Jenny Bindon at the end of a blitzing counter attack before slotting the ball into the back of the net.
"They really pushed forward in the first 10 to 15 minutes and we were lucky to hold on there and Brianna pulled out a few good saves,'' Matildas captain Clare Polkinghorne said.
"Any goal that comes against the run of play dampens their mood a bit, which is good.''
The Matildas grew in confidence in the second half with Samantha Kerr and Katrina Gorry narrowly missing shots at goal.
Hearn had a chance to level the scores for the visitors late in the match from a cross, but drilled her shot into a defender.
While the win extends the Matildas' remarkable 23-year unbeaten streak over the Ferns, the two sides will meet again in Canberra on Sunday to battle it out for the Centenary Cup.
- AAP