The 21-year-old netted the second of the three goals after neat interplay on the edge of the box provided him with a shooting opportunity.
It capped an impressive display from the former Ajax Cape Town player, who is rapidly becoming a favourite in Amsterdam.
His new coach, Frank de Boer, said last week even he had been surprised with the talent of the rising star.
“Everyone told me how good he was, but even then he surprised me,” De Boer said. “Serero is a player with talent dripping off him. He is incredibly quick and a very clever player.”
Meanwhile, Bidvest Wits’ Sifiso Myeni played the final 14 minutes of the match for Brondby, where he is on trial.
The winger only arrived in Denmark earlier this week, but got his first run-out against Ajax as part of a 12-day trial.
With almost his first touch of the game he created a great opportunity for teammate Osama Akharraz, but the latter could not finish.