Van Persie hit a spectacular double in victory at the Liberty.
Vorm knows Van Persie better than most as the pair are part of the Dutch international squad, and the Swansea goalkeeper also heaped praise on his compatriot.
He said: "The problem with Robin is you never know where he is going to put the ball. He scored the first goal with an incredible volley with his right foot and then the second one was an amazing shot with his left foot. It is so hard even when you know him well you can't work him out. I think he is in the top five players in the world at the moment.
"Even though he is an opponent he is a joy to watch. He can only help to make you better because you have to be on the top of your game against him. Otherwise you can see what happens. It is a shame he doesn't play for us."
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