Carlsen has so far won 4 games in the first half of the 10 rounds match. In the sixth game Carlsen with leko came out a draw. Here the game. My question is what do you think of the 41st move ? why Nf5 why not Bc4+(mistake here is does not give check) winning the rook ? 

I think you misjudged the position of White's king, as 41...Bc4 is not check.

41.Bc4 isn't check lol.

huh ? yeah you are right guys I was pretty sure last night The white king was on f1 or e2 sq ? 

A Knight vs. Rook Endgame?! I think the Knights are coming back strong, kco. LOL

ADK

Ok, maybe the better question would be then, could Carlsen have done it better ? 

LOL, kco. Dont drink and watch GM games.

damn, Carlsen played good in the end game, i mean, i woudve lost if my opponent had a rook and i didnt... i just fail when it comes to moving a knight strategically

which end game option would have been better for Carlsen?

Rook vs Bishop?

Rook vs Knight?

i mean, clearly he managed to make it with the knight, but Leko rejects trading bishop for knight in move 40, whilst setting up the bishop for bishop trade in move 42.

I am not sure what Carlsen's style is in the endgame.  

from memory, Fischer really good with the Bishop in endgames..