England Under-21 ace Ward-Prowse, 19, has been dubbed the south coast's answer to David Beckham because of his set piece skills.
But Koeman says it is unfair to compare the teenager with Manchester United hero Becks.
The St Mary's manager said: "Ward-Prowse is a great player and I told him this week he had a big future, but comparing him to Beckham puts a lot of pressure on the boy because Beckham was an amazing player.
"He's already played a lot of matches in the first team and is a boy from the academy.
"He's a great player, because he's left-footed, he's right-footed, he has a good feel for good positions in the midfield and at set pieces he's an important player."
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