The midfielder was introduced as a substitute in added time at Wembley Stadium, as the Dutch came from behind to win the friendly match 2-1.
Clasie, who started in last week’s 3-2 defeat to France, told Southampton's official YouTube channel: “For us it was an important game because the last few matches we haven’t picked up good results.
“I think the team did it very well, they played compact. It was a difficult game and we knew that before. Nothing is better than a win and a good result, so well done to the boys.”
While the Dutch have not qualified for UEFA EURO 2016, Clasie believes some encouraging signs for the future are starting to show.
“We have many young players in the team,” he said. “For the coaches and the people around the coaches, we help them, it’s important to build a new team. Old players left them a bit behind, so they select young players and give them chances. That’s good for us.”
Clasie and his fellow Saints and Netherlands teammate Virgil van Dijk will now head back to the south coast ahead of the trip to Leicester, as Ronald Koeman’s side look to improve their European prospects against the Premier League leaders.
“I will drive back with Virgil and Thursday, [when] we have to train again. Then the focus is on Leicester away. But we have six or seven matches to go, hopefully we can take our points so that we can stay where we are in the table, so I look forward to it.”