Allardyce handed Morrison his full debut against League Two Cheltenham and the 20-year-old former Manchester United starlet marked it with a stunning goal as the hosts eased into round three with a 2-1 victory.
"He's not bad, is he?" said assistant boss Neil McDonald.
"He scored some good goals in pre-season and he's had to be patient, but he's come out and showed what he is about.
"He showed composure, he's knocked on the door and that's what the manager wants. He adds to the competition for places that we want on the pitch."
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