And now after a year at the Liberty Stadium, the Samoan star is convinced Tipuric can go on to be just as good as the former IRB World Player of the Year.
"I rate Justin very highly. I would pitch him very close to Richie McCaw," said Fotuali'i.
"He's a young and talented player.
"Supporters might not see too much but when you are out there on the pitch you see all the work he gets through: the tackles, stealing the ball and everything else."
Like McCaw, Tipuric has been given the responsibility of captaincy from an early age and the Trebanos-product regularly leads the Ospreys in Alun Wyn Jones' absence.
Again, Fotuali'i sees similarities with the man who led the All Blacks to World Cup glory last autumn.
"Richie is a smart, talented player and an awesome leader. That's exactly what Justin is," added Fotuali'i.
"He leads by his actions and the boys follow him."
Tipuric, who made his Wales debut in last summer's clash with Argentina, is in line to face the Barbarians next month, ahead of Wales' tour of Australia.
And with skipper Sam Warburton having been struggling with injury, the 22-year-old could lock horns with Wallaby sensation David Pocock Down Under.
"It would be a great challenge for Justin this summer against David Pocock, who is another awesome player and so strong over the ball," continued the Samoan.
"They are slightly different players: Justin is a good ball carrier, he's very quick and has all the skills - he could play in the backs if he wanted.
"It will be a great test for him to face the Wallabies. I'm really looking forward to those games and reckon Wales have a good chance."