Van Dijk is set to captain his country in their crunch Nations League clash against Germany on Monday, knowing a draw will be enough for the resurgent Oranje to top Group A1.
The 27-year-old has also worn the armband for Jurgen Klopp's side this season, having had a transformative effect on the Reds' backline since joining for £75 million ($100m) from Southampton in January.
"He is in the top 10 for sure. He's so big and so good. I think he plays so well every week for Liverpool.
"With the national team he is the captain now, so he is really important for Holland."
Van Dijk and Liverpool fell at the final hurdle in the Champions League last season, going down 3-1 to Real Madrid in the final, and Klaassen thinks they could make another tilt for European club football's greatest prize.
"Last year they were close and nothing is impossible," he added, with the Premier League team's vital Group C showdown against Paris Saint-Germain to come next week in the French capital.
Van Dijk has played every minute of the Premier League and Champions League for Liverpool this term, and will make his 24th appearance for the national team when they take on Germany.