Tynecastle boss John McGlynn named seven players aged 21 or younger in Saturday`s semi-final victory over Inverness at Easter Road.
On-loan Liverpool striker Michael Ngoo was among that fresh-faced group and he can certainly expect to feature in the Hampden final in March after a bullish display on his debut, just 24 hours after moving north from Anfield.
The 20-year-old made a fantastic first impression as he fired home a terrific volley to cancel out Andrew Shinnie's opener for the Highlanders in the 1-1 draw that was only settled by a 5-4 penalty shoot-out success for the Edinburgh side in Leith.
Now MacDonald has told the others - Fraser Mullen, Danny Wilson, Jason Holt, Callum Tapping, Scott Robinson and Jamie Walker - who shone against Caley to continue playing like they are if they want to feature in the showpiece decider in Glasgow in six weeks' time.
He told Press Association Sport: "The young boys were fantastic. Not only with their work rate but at times we tried to play some football, some nice one-twos.
"The three boys in the middle of the park - Callum, Scott and Jason - were great and we also had Michael coming in too. He was fantastic. He only arrived on Friday but held the ball up, laid it off, won things in the air and scored a fantastic goal.
"Now it is up to those lads to stay in the team until the final. They have set a standard now. They need to maintain that if they want to keep their spot.
"We have other good young boys coming through who will want their shot. The lads who played against Inverness will need to fight to keep hold of their jerseys."
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