The Southampton manager is confident new signing Clasie will fill the void left by Schneiderlin.
Schneiderlin brought an end to months of speculation by moving to Manchester United on Monday.
Koeman was quick to react, bringing in Clasie - with whom he previously worked at Feyenoord - on a five-year deal.
The Netherlands international made his debut in Saturday's 3-0 friendly win over Groningen and Koeman believes Clasie is a good fit to replace Schneiderlin.
"He's a perfect replacement for Morgan in that position," he told Sky Sports.
"I know that because I worked three seasons with Jordy.
"Of course, he's still not Schneiderlin but he's still young. He has to develop and adapt to the Premier League and its intensity but he's a great signing."
