Pulis, who is relishing the opportunity to take his Stoke side to Old Trafford for the final chapter in the title battle, believes United still have "a great chance" of lifting the Premier League trophy.
That would mean a victory over Pulis' Potters of course, with the Red Devils also relying on a favour from Wigan at Chelsea.
Should the Blues slip up against Latics then it will open the door for Ferguson to claim a record 19th English league title for United.
"It's a big testament to him.for his age," joked Pulis momentarily.
"He's built that football club up. And I don't think people will see that until he actually retires.
"You don't get the recognition until you move away from the post you're in.
"In my opinion he's most probably the greatest manager this country has ever seen."
Stoke face the reigning champions having not long got over the nightmares of their trip to face the team close to stealing United's title.
The Potters endured a day to forget against Chelsea two weeks ago, going down 7-0 as Salomon Kalou and co ran riot.
Stoke's Premier League status was already secure when they made the trip to London, but Pulis does not want his players to be similarly laid back tomorrow.
He said: "I hope it (the pressure) is not off as much as it was when we walked into Stamford Bridge.
"That's very, very important that we don't have that mentality because United are such a good side that they can do what Chelsea did to us, without a question of doubt.
"So we have to make sure that is spot on and we're ready when that whistle goes."
Stoke, currently 10th, have enjoyed another superb campaign among England's elite - dispelling the threat of second season syndrome.
And ahead of the final day, Pulis is hugely looking forward to playing a part in the tightest title tussle in years. "It's a great game for all the players, they're the games you go into the Premier League to play," he said.
"We're really, really pleased that it's at Old Trafford. "They (United) have still got a great chance of winning the title.
"A lot of people think Chelsea are going to win it because they only have to turn up.
"But I'm sure Roberto (Martinez) will be looking forward to that game, he'll make sure Wigan give it a right crack.
"And they certainly won't want to be in the position that we were in a few weeks ago where we got hammered."