The 23-year-old Chippa United defender put in an outstanding performance to steer his side to the final of the friendly international competition.
Zimbabwe next face Zambia in the final on Tuesday after Chipolopolo beat Malawi in the other semi-final.
Reflecting on the game, Marinica heaped praise on the young centre-back, who came on in the 20th minute after an injury to Munashe Garananga.
"There are players who had the chance today. I believe that every single player should be ready," explained the head coach.
"I actually don't call them substitutes. I call them impact players. So, every player that comes off the bench has to make an impact.
"And Mauchi’s done fantastic for himself, and he's proven that the time he has spent with the national team, even though he didn't have a chance to play, he is a quality player, and he came in, and he slotted in very well."
Botswana will face Malawi in the third and fourth-place play-off on Tuesday.
Zimbabwe midfielder Marshall Munetsi says the Warriors are eager to measure themselves against the Super Eagles ahead of their highly anticipated Unity Cup clash next week Tuesday, 26 May.
Kaitano Tembo has been appointed Zimbabwe interim head coach following the resignation of Mario Marinica.
Representation for Zimbabwe international Blessing Muzarabani has claimed the player did not breach any contract with the Pakistan Super League when he signed with Kolkata Knight Riders to play in the Indian Premier League.
Australia are set to grace Zimbabwe with their presence for a three-match ODI series this September.
