The talented youngster was edged out in the final game of his section by David Axon of Wales who won all five matches.
However, MacDonald fought back from losing the first set 11-5, having trailed 8-0 after just three ends, to take the second set 10-3 and force a three-end sudden-death tiebreaker.
On this occasion MacDonald started well and was 8-0 in front after four ends.
In the shoot-out though the Welsh ace counted singles on each of the first two ends for an 11-5, 3-10, 2-0 victory.
Results elsewhere in the section conspired to ensure MacDonald stayed in second place with England’s defending champion John Wells losing.
Wells, from Hartlepool, had seen his closing group match delayed for several hours after he had been admitted to hospital in Belfast for toxic tests after a gas leak at the hotel where the official World Bowls party, including MacDonald and Gaynor Thomas, were staying.
MacDonald later admitted: ‘My feelings are a mixture of delight and relief! I felt I played well against David Axon who had not dropped a set all week until our contest.
‘It is great for Jersey bowls to still be involved at such an advanced stage in such a prestigious international tournament.
Nicky Donaldson has coasted through to the last four and is an experienced campaigner but I’m up for the challenge and looking forward to our game.’ In her final game of her section in the Ladies World Championship, Gaynor Thomas was beaten 11-2, 5-6,0-2 by Mary Alderson from the Isle of Man.
