a near miss
This game is number 29 in New York 1924 by Alexander Alekhine. Here we have Geza Maroczy with the white pieces against Frank Marshall's Petroff Defense in Round 6 of the famous tournament.
This game has no wild swings from winning to losing but features Maroczy patiently developing the small advantage given to him by Marshall at 18 ... f5 into the full point.
Marshall, handling so carefully his rook in the endgame, forces Maroczy to play flawlessly and with vigor.
Maroczy cleverly "gains a decisive tempo" with moves 58 to 61 by using the technique of triangulation.
According to Alekhine, the "decisive" move is 63 b5. This move initiates a series of seven moves culminating in two united passed pawns for White. After ten more moves, Black resigns.
I've included the entire game here along with Alekhine's annotations but what interests me mainly is a mate that almost was. Specifically, at move 74 ... Rxh4+. If instead Black had played 74 ... Kf2, White would have had to play 75 Rf7+ to prevent 75 ... Rxh4 mate. Potentially then we have 75 ... Kg3 77 Rxg7+ Kh3 78 a5 Ra4 79 b7 Ra1+ 80 Rg1 and wins.
Apparently, in the variation beginning 48 Qe8+, Alekhine has imagined Black as having played 47 ... Rf6.