Personally, I think that Carlsen's greatest opponnet hasn't arrive yet. Analysing his games and scores in general, Carlsen is slighty better than all of his opponents. Well, after all, he is the world champion...
I think no one is able to dethrone Carlsen yet. I could even bet that he is going to sit on the top of the chess' world for at least two or three more years.
Vishy Anand.
Chuk Noris ?
Can anyone tell us Carlsen vs Giri head to head.
You guys are all wrong... it's Nakamura! 
Vishy Anand.
No, that's wrong according FIDE database.
In which we can see how Carlsen could be better than Anand.
I find the fact that Anand was able to play a World Championship final match as a contender against Carlsen carries rather more weight than those slightly meaningless statistics.
You guys are all wrong... it's Nakamura!
No, no. Nakamura have never beated Carlsen.
Learn about sarcasm.
You guys are all wrong... it's Nakamura!
No, no. Nakamura have never beated Carlsen.
Learn about sarcasm.
Well,as Petrosianpupil correctly pointed out,we have two striking cases in which the contender had suffered quite a few losses without ever(!)having beaten the Champion before their match.Capa in particular had a 5-0(!) score vs Alekhine before their match,no wonder he underestimated him.So,you never know!
Almost everyone in the top 10 poses a threat to Carlsen but since the question asked is for one, I would go for Aronian in Classical chess, Caruana in Rapid and Nakamura in Blitz.
P.S Although the challenger for the world championship is Vishy, in my opinion, he does not offer as much threat to Carlsen as those mentioned above.
It's Nakamura, BECAUSE he has never beaten Carlsen. Such opponents are the most dangerous
#Alekhine#Fischer
Anand is also very dangerous. I suppose each of the other contestants are.
FM Abdusattorov Nodirbek from Uzbekistan.
At the age of 11 he is rated 2436, ranked first in U-12.
FM Abdusattorov Nodirbek from Uzbekistan.
At the age of 11 he is rated 2436, ranked first in U-12.
Wow!Impressive indeed!
Wei Yi. Give him a few years, and Yi-Carlsen will be like Alekhine-Capablanca. (Without the bad blood, we hope!)
I fail to understand the analogy.
Wei Yi. Give him a few years, and Yi-Carlsen will be like Alekhine-Capablanca. (Without the bad blood, we hope!)
I fail to understand the analogy.
Those two were far and away the strongest players of their time. Maybe I should have said Karpov-Kasparov?
Yeah, but the thing is, both of those pairs had their rivalry and personal relations, keeping correspondence and such.
Maybe I missed it, but I don't think that Yi and Carlsen even played a single game.
Have they even met?
In fact, any of the top ten players in the world has a significant chance of dethroning Carlsen. People overestimate the security of the champion's title, routinely. There is no need for anyone to jump 60 to 70 ratings points to beat him.
If we accept that ratings are actually a true measure of the player's relative ability, even a 75 point ratings difference is not as great as you may imagine. For instance, if a challenger plays a 12 game match against the champ, and the challenger is the worse player, 75 points behind in rating, there is still a 10% chance that the worse player will win the match. Really. A 12 game match is not a surefire way to determine the best player between two opponents who are that close in ability.
Expect upsets in chess, they happen.