Dominant Dutch breeze past Finland
The Dutch, the number one side in FIFA's world rankings, went ahead after 29 minutes when Wesley Sneijder lobbed the ball forward for the 21-year-old Strootman to beat keeper Lukas Hradecky with his first touch.
Strootman was injured moments earlier and had only just returned to the pitch.
De Jong, who came on for Klaas-Jan Huntelaar in the second half, made it 2-0 from close range deep into stoppage-time.
Finnish midfielder Perparim Hetemaj was sent off after receiving his second yellow card on the hour.
"I am satisfied with the number of chances we created against very defensive opponents," coach Bert van Marwijk told Dutch television.
"Our passing game was excellent today but we could have controlled the ball better in the final third of the pitch."
Captain Mark van Bommel added: "We were sloppy and missed too many chances".
Finland captain Niklas Moisander said a couple of lapses of concentration cost his team.
"If you doze once or twice against a top country you will lose," he said.