Wales aren't exactly blessed with a wealth of potential replacements - not so long ago Newport Gwent Dragons No.2 Lloyd Burns was plying his trade as a bricklayer but now he looks set to marshal the front row in New Zealand.
But Fitzpatrick believes those who have written Wales' chances off already should think again.
Back in 1987, fellow hooker Fitzpatrick, who collected 92 caps for the All Blacks, was a late call up to the New Zealand squad for the inaugural World Cup as skipper Andy Dalton was ruled out with a hamstring injury.
He went on to guide New Zealand to the William Webb Ellis trophy back then before skippering the All Blacks 51 times - and while Wales have suffered a similar fate to the 1987 Kiwis, Fitzpatrick believes 22-year-old flanker Warburton, who only has 13 international starts under his belt, can fill the captaincy void.
"Wales have to move on, but injuries are a cruel thing and to be ruled out of a World Cup at this late stage is a real blow and a body blow for Wales," said Fitzpatrick.
"But I think they saw on Saturday with Sam Warburton, I think the young kid did a great job and didn't seem to be too inhibited by the leadership.
"That's the amazing thing in rugby and teams, he's been thrown in at the deep end and he's done an amazing job in the last few weeks captaining the team.
"To lose a player of Matthew's calibre is huge; I think the guy who played on Saturday was laying blocks last week so depth could be an issue.
"It's very sad for Matthew but an opportunity for other players as we've seen in previous World Cups. It was exactly the same situation for me, I got an opportunity but it's how you take those opportunities and how you deal with it as a team."
While Rees' absence is sure to be felt in New Zealand, Wales didn't seem to miss him too much against Argentina, notching up a 28-13 win over the Pumas.
And while Rees has been ruled out of the World Cup and Gethin Jenkins will miss Wales' opener against South Africa, Adam Jones is expected back to face the Springboks - and Fitzpatrick believes both props are crucial to Warren Gatland's side.
"Gethin Jenkins and Adam Jones are two world class players," he added.
"They have shown that they are world class. Them coming back into the fray is a real boost because it was an area of concern for the Welsh on Saturday.
"They have got a big group in terms of powerful, the scrum will be a key area but the breakdown as well as we saw on Saturday. And Warburton and co seemed to really dominate England there."
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