So far this season, summer signing van Persie has netted 11 goals in all competitions, Javier Hernandez has six, and although Wayne Rooney has not been his usual self with just three, Ferguson is pleased with the work that is happening in the United final third.
"Wazza will get to 20 goals plus I'm sure of that," said the United boss who is confident the England international will soon start to fire.
"It's a healthy combination we've got up there.
"Robin is experienced. Eight years at Arsenal helps and he's come to us at the right time, there's no doubt.
"He's got us 11 goals so far and Chicharito's on six and getting back to what he was a couple of years ago and a summer of rest has helped enormously.
"He's looking fresh and aggressive with his running always a handful."