The Bafana Bafana forward applied a neat finish to a counter-attacking move on 28 minutes as Ajax took an 8-0 first-half lead and then took their foot off the gas.
The result should be viewed in the context of the opposition, but what will be hugely pleasing for Serero is the 63 minutes he managed on the field of play before being substituted.
The 22-year-old is desperate to return to full fitness after being plagued by injuries in his first 12 months in Amsterdam, following his much-publicised move from Ajax Cape Town in May 2011.
With most of the Ajax players replaced at halftime against Oldenzaal, Serero was given an extra 18 minutes on the park and can now look forward to building on that in the next friendly against BVO Emmen on Saturday.
Later in the pre-season programme Ajax have a home match against Scottish champions Glasgow Celtic, before they tour England with matches against Premiership sides Norwich City and Southampton.