OK, so here's the question: How much can fatigue affect a player's performance?

Only yesterday Caruana played a seven-hour, 106-move draw. There was a 36-move queen-and-pawn endgame, during which Caruana had a tablebase-win for many moves before the game ended in a draw.

Might his blunder today be due, at least partly, to exhaustion from yesterday's game?>

https://www.youtube.com/watch?v=_yj...

Instead of 17 Bg3, 17 Nc4 proposes to remove the black N on e5 that keeps White's king's bishop out of c4. If Black declines the offer by 17...Re8 18 Nc4-e3 prepares the move Nf5

Instead of 18 f4, 18 Nc4 proposes to exchange knights. An additional justification is that this knight is White's worst placed piece and 18 Nc4 puts it to work before doing anything else.

19 e5 opens lines in a position where White has neglected to put his queen's knight to work. The effects of this remain to be seen.

So if Caruana had taken the knight with 22. exf6:

As for Caruana being <tired>, who wouldn't be, in his situation? Plus Carlsen (or no player at that level, really) would surely not give him a break choosing to play a quiet game. And in any event, Caruana himself is not inclined by temperament or repertoire to play a quiet game with the white pieces anyway.

What I referred to as 'unconsolidated space', I might easily have called 'unfortified' (space).

In a game of chess where White - or Black - creates many squares of elbow-room within his own Pawn chain, provided he has full control of those squares (with his own pieces), then his extra space is strong (fortified or consolidated, as I understand it to mean); but, if the opponent possesses greater control (of the squares within one's own Pawn chain), then one's own extra space is 'unconsolidated' (or 'unfortified', as I understand it to mean).

In the game above, although it was White that created the greater space in the center... by move fifteen, however, it was Black who had the greater control of it (the central squares).

The squares within the pawn chain would be what - b2, c2,d2, c3,d3,d4?

And if White has bishops at b1 and b2 (s)he would be controlling those squares pretty well - so they'd be consolated as far as White is concerned? What about a1, b1, c1, d1?

Don't worry about other kibitzers's qualifications. It seems an interesting concept I haven't come across, and at the moment I'm interested in the idea of controlling squares.

Interesting idea in controlling squares is Fischer's "To get squares, you've got to give squares." But there's giving squares and really giving squares.

Here, looks like Caruana idea is to pressure the dark squares ...d6...c7 pawns. Hopefully, with help from Nc4. Seems to accomplish it but in doing so gives up a lot of light square holes. And the potential Nc4, Bb3 structure doesn't appear very stable.

So seems he drops Nc4 idea and tries to put up some defence of the light squares with 22. Bc2. But appears a tempo too late as 22...Qd5 causes all sorts of concessions where white just about falls apart.