The Dutchman stressed on the need to score early goals to put pressure on their rivals.
"The practice matches were a huge learning for the team. While we won the match against France we narrowly lost to Belgium. But what came out for me from the matches was that we have to increase the pressure on the opponents from the start," Van Ass said.
"While the boys did a good job in the practice matches in breaking the opposition defence, they need to ensure they yield results. Getting the initial goal in our name will help us build the pressure," he added.
He was also pleased with the way Indian defence, its perennial problem, fared in the practice matches.
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"The defence looked strong in both the matches. While we conceded two goals against Belgium, the positive that I take from the game was that the boys have now started to close the gaps," Van Ass said.
"Our first match is against the host team, Belgium. They will have just one advantage over us, they will be playing in front of their home crowd. Besides this, I think the teams will be evenly matched and all will depend on the initial pressure," Ahrens said.
"I think we have a strong attack and I am confident of a good start."
While Indian women's team will open their campaign against Belgium, their male counterparts will clash against France in their first match.