Louis van Gaal - going into his final competition as Holland coach before making the move to Manchester United - will demand an improved effort from his side after their 1-1 draw against Ecuador was followed by a narrow 1-0 triumph over Ghana.
Ahead of June 13's Group B opener against world champions Spain, Van Gaal has one game remaining to assess his side and he will hope some of his players take the opportunity to get closer to their best form.
However, he was left frustrated by their showing against Ghana later that day, describing his players' performance with the ball as "careless" as the Dutch missed a host of second-half chances.
Captain Robin van Persie has scored six goals in his last six games for club and country, including one each against Ecuador and Ghana.
"If Wales play with a striker, it is pointless to play three (central) defenders... so it is 4-4-2," he said on Monday.
"What is important is that Van Persie does not do too much work. On Saturday against Ghana, Robin did too much. He was behind the right-back too often, and at times (with) the left-back.
"It's a little better each day with us, I think but will that be enough against Spain, Australia and Chile? I do not know.
"If you look at the results in practice matches, we do not do bad."
Van Gaal will be without Jonathan de Guzman for Wednesday's game due to a hamstring complaint.
Wales, who will be without Real Madrid's Gareth Bale and Arsenal's Aaron Ramsey, have shipped 13 goals on the Netherlands, including a 7-1 hammering in 1996.
However, they go into Wednesday's clash in reasonable form - unbeaten in four and off the back of a 3-1 win over Iceland in March.
While Chris Coleman's men are not involved in World Cup action, they will use the fixture as a warm-up for their first Euro 2016 qualifier against Andorra in September.
"Both sides have their own agendas. The Netherlands will be fine-tuning for the World Cup in the summer, but for us, this is a vitally important game with a view to the Euro Championship matches that start in September," he explained.
"Even with Gareth and Rambo (Ramsey) missing we still have a strong squad and I am certain that we will give the Dutch a good game."
