The Scotland international and third seed won through his fourth and fifth round ties on Thursday to book a place in the last eight of the national championship.
On Thursday morning, McDonald beat Conor O'Neil (Pollock) by 3 & 2 to set up an afternoon fifth round match against local player Greg Smail (Craigielaw) whom he beat by the same margin to secure his place in the last eight.
In the quarter finals on Friday morning, McDonald will take on Craig Ross (Kirkhill) for a place in the semi finals.
James Bunch (Prestwick) lost by 2 & 1 to Allyn Dick (Kingsknowe) in their fourth round tie on Thursday morning whilst his Prestwick GC clubmate Charlie Macneal was edged out at the 21st hole, alsdo in the fourth round, in his match against Ewen Ferguson (Bearsden).
The quarter final and semi final matches are scheduled to be completed on Friday.