The Hoops host the German outfit in the important group stage clash in Europe's second tier competition and are in dire need of a win to keep their hopes of progressing to the next round alive.
Celtic are currently on the bottom of Group C with one point from two matches and McDonald outlines that three points against Hamburg is vital.
"We understand our position in the group and know we need to get three points in front of the home fans," the Australian striker told tribalfootball.com.
"We really need the crowd to come in their droves and act as a 12th man to help give us that extra motivation required to get over the line.
"Hamburg are a very capable team as we saw with their 4-2 victory over Tel-Aviv last time so we need to be at the top of our game."
In the other Group C clash, Israeli club Hapoel Tel-Aviv host Austrian outfit Rapid Vienna at Bloomfield Stadium.