"She just missed out last year, but in our heart of hearts, we always felt she was up to it."
The Map is a rising six-year-old and is still reaching full maturity.
MacGillivray said continued work had been instrumental in producing the product The Map now is.
"She's kept eating, as she just keeps getting more and more self-assured," MacGillivray said.
"Every time she comes out, she does it a bit easier, and it was a beautiful ride from Damian Lane.
"He sat in there amongst all those horses, he didn't get anxious, he let her do her thing.
"Once she was out, there was no stopping her."
MacGillivray did have a few anxious moments inside the final 200m when The Map was fighting out the finish with Excelleration.
The Richard Cully-trained Excelleration nosed out The Map in the Group 2 Adelaide Cup (3200m) at Morphettville in March and MacGillivray had flashbacks of that finish.
It is expected Jamie Kah will stick with The Map in the Melbourne Cup having ridden the mare on three occasions, for two wins and the close Adelaide Cup defeat.
Kah rode the mare to victory in Adelaide on May 4, but commitments in Brisbane forced her north on Saturday.
"It's Jamie's ride for sure, but I'm happy to be the fill-in in a $500,000 race and get the job done," Lane said.
"It's an important race for them to get into the Melbourne Cup and they can plot a path now.
"She settles really well in the run, stays well, and she got the job done well today."