While Marshall has a full squad to select from, Greatholder has been hit hard in losing his greatest attacking weapons with Sean Lovemore and Jarrod Smith gone for the season - and probably a lot longer.
A 3-0 win will not be enough to get the visitors back into the contest but Marshall has no intention of playing for a draw or even a low-scoring loss.
"We need to play as well as we have all season," said Marshall. "Both on attack and defensively."
Canterbury coach Keith Braithwaite is under no illusions when contemplating the task ahead against Auckland City but takes confidence from the first leg where the Dragons went down 2-1.
"If we play as well as we did on Sunday and have a bit of luck I'm sure we can make a decent go of it," said Braithwaite. "We just have to put away our chances. Their keeper made a couple of excellent saves and we hit the post so we were not without a chance. They had two clear chances and took them both."
If Canterbury lead 2-1 after 90 minutes, extra time will be played. A 1-0 Canterbury win would put City through as would any draw or home team win. A 2-0 - or bigger - Canterbury win would be enough for them to win through.