The Holland striker has now gone nine games without scoring, and managed just one in his last 12 appearances for the Old Trafford outfit.
It is Van Persie's longest dry spell since he arrived in England from Feyenoord in 2004 and represents a marked contrast from the free-scoring form he showed immediately after his summer move from Arsenal, which led to him being tipped by many to receive player of the year accolades.
Not even finding the net for his country recently has triggered an upturn in his club fortunes, with the effort he hoped to be awarded at Sunderland last weekend being credited as a Titus Bramble own goal.
With Wayne Rooney set to return from a groin strain, it seemed the time might be right for Van Persie to be given a brief rest.
However, speaking ahead of Monday's Manchester derby at Old Trafford, Ferguson has confirmed that will not be happening.
"Robin doesn't need a rest, that's for sure," the Scot said. "He's a strong lad with a great physique. It's disappointing he wasn't awarded the goal at Sunderland -- I can understand that because it took a wicked deflection.
"But the shot was fantastic -- it was hit with such venom that it's not surprising it took a deflection.
"His ability to manoeuvre his position at that point was excellent."
In previous years, Ferguson has found himself answering questions about Rooney's lack of goals, before the Merseysider exploded again.
As a former striker himself, the Scot is uniquely placed to offer advice in times of such strife.
And, while he retains a firm belief Van Persie will turn his present situation around, he always remembers the wise words his dad came out with.
"My dad always used to say 'make sure you batter the ball -- don't tap it or try and side-foot it into the net'," Ferguson said.
"That's what I always tell strikers too. If the goalkeeper saves it, you can say 'what a great save'. But if you try to side-foot it and the keeper catches it easily you get criticized.
"The goals will come. All strikers have little dry spells. You have to get through that period and not lose your faith and belief in yourself."
Monday's derby encounter is a reminder to the previous meeting with Manchester City this season, when Van Persie rattled in a stoppage-time free-kick to give the visitors a precious win.
It was part of an impressive sequence of results that have allowed United to amass a 15-point lead at the top of the Barclays Premier League which surely will not be lost over the final eight games, even if Roberto Mancini's men emerge triumphant.
City skipper Vincent Kompany has already spoken of his desire to make the game into a one-off championship of Manchester -- something Ferguson understands.
"It'll be a big game for City -- they'll want to come and derail us for a spell," the United boss said.
"I can understand their motivation -- we'd probably have the same thing.
"There will still be a great intensity about the game. It's the only game and it will be shown all over the world. That does seep into the fabric of what the game will be like for both teams. You can't dismiss that."
The prize for United is three points that would leave them requiring only four more to claim a record 20th title.
In addition, they would be on track to eclipse Chelsea's record points haul of 95 from 2005.
Not that Ferguson is expecting too much credit for it.
"We've only got eight games left," he said. "It's a bit late to give credit now.
"The way we've approached things is the correct way and that's to win the next game. Hopefully it takes you to winning the league. Then we talk about what the season has been like.
"It doesn't matter what people say outside the club -- it's about what we think about what we've achieved inside it.
"The staff I have are more critical than anyone -- and we're always looking to do our best.
"I think this season has been a good one for us."