Pocock and Folau missed last weekend's quarter-final win over Scotland because of injuries and were in doubt for the clash with the Pumas at Twickenham.
Both men had to pass last-minute fitness tests before being selected in the starting lineup but Cheika said he was not taking any risks.
Number eight Pocock, who injured his calf in Australia's final pool match against Wales, is improving day by day and will be close to peak fitness by kick-off.
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“We’ve calculated where he’s at with recovery time,” Cheika told a news conference on Saturday.
“We always knew that injury would be around the seven day, eight-day mark for return to play.
“He got through a good deal of training yesterday, more than we thought. Every day you’re going to get improvements."
Pocock is considered pivotal to Australia's chances against the Pumas because of his high-work rate and ability to create turnovers.
Cheika said the powerfully-built forward, who has struggled with injuries in his career, was determined to play.
“He's very strong mentally, that lad, so it would have been very difficult to stop him even if he wasn’t fit," he said.
“We feel more than comfortable with the fact he’s fit enough to do his job and do it very well.”
Cheika was also pleased by Folau's improvement, saying the fullback remains one of Australia's most dangerous attackers.
“As great an individual player as he is, he’s very much a team player,” Cheika said.
“He’s certainly not driven by always being the main man.
“But I would...guess that a player of his calibre is only going to enjoy these matches and do really well in these finals matches.
“I think he’s just been wanting to play footy, I think the frustrating part was not being able to play last week.”
Australia, world champions in 1991 and 1999, go into Sunday's match as slight favourites and while Cheika is confident of winning he said there was no complacency in his team whatsoever.
"I feel like we are really ready. We are looking to improve all areas of the game," he said.
"I have known Argentina's players very closely for many years. They made the semi-finals in 2007. They are a very strong team of players.
"They are very strong and passionate about what they are doing. They have just transformed the way they have played. They have always had a steely approach to the game and tournament play has always suited them."
"This is a great opportunity for us to progress. It is all about confronting the opponent on Sunday over 80 minutes."
(Editing by Ed Osmond)
