Women's hockey: England takes 4-1 win over Wales
But Wales, who had rarely threatened the England defence, pulled a goal back late on when forward Sarah Thomas drifted easily past four defenders before beating Beth Storry in the England goal.
Cullen made up for some poor finishing from the England forwards and head coach Danny Kerry admitted that his side must improve in front of goal if they are going to win gold.
He said: “We need to set high standards and we expect high standards from out teammates if we had done that that today it could have been double figures.
“I am happy with the performance just really disappointed with our play in the attacking circle. If we don’t have that application in the circle we won’t win Gold,” added a downbeat Kerry.
Captain Kate Walsh was also concerned that England could only score four goals considering the high percentage of play they had in Wales’ half, she added: “We’ve got to be ruthless in these games, as the goal difference might count at the end of the tournament. We have to put in a gold medal winning performance every game.”