The Nelson Mandela University outfit were pushed all the way by the Tshwane University of Technology Vikings but held on for a memorable 34-31 victory at the Madibaz Stadium in Gqeberha.
Van der Merwe was thrust into the leadership role after regular captain Arnouw Nel had been ruled out with injury and rose to the challenge with a performance that earned him the Player that Rocks award.
"It was very close, but I think we managed the pressure moments well by staying calm and sticking to our processes," said the 21-year-old loose forward, who crossed the line in the second half for what turned out to be a vital try. "I believe that won us the match in the end."
Even though the home team came up trumps in front of an appreciative crowd, the skipper admitted that there was room for improvement.
"It wasn't a perfect performance, but we are happy to start with a home win. We'll revisit our mistakes and work to rectify them against the University of KwaZulu-Natal on Thursday."
Van der Merwe, who played his schoolboy rugby for Paarl Gymnasium, made his debut for the Madibaz in the Varsity Cup last year.
"That was at home against UP-Tuks," recalled Van der Merwe, who usually does duty at eighth man. "It was memorable as I had all my friends in the crowd and family watching at home."
From what he has witnessed thus far, the fourth-year biokinetics student believed this year's Varsity Shield would be extremely competitive "with no easy games".
"Everyone is fighting to win the title to gain promotion to the Varsity Cup, so we are preparing for many similar challenges. We'll have to consistently bring our 'A' game."
Although he was singled out for his performance on the night, Van der Merwe acknowledged that it was a team sport.
"I couldn't have done it without my teammates providing me with the opportunities to express myself. It's always nice to contribute to a team victory in front of your home fans."
He was full of appreciation for the Madibaz supporters who ventured to the stadium en masse.
"They were our 16th player and we are hoping for similar support for our next home game [against Cape Peninsula University of Technology on March 9]."
In addition to maintaining their composure in pressure situations, Van der Merwe, who was born and bred in Durbanville in Cape Town, said they were readying themselves for a physical challenge this week.
"UKZN have a big pack and we'll have to man up in that department. We'll have to be better in our set pieces as they will target the scrums and lineout mauls."