"Almost nothing was known about this exception to the general rule that two extra pawns generally win. (A previous example Albin - Weiss, Vienna 1890, drew little attention) With a rook pawn and a bishop pawn the winning task is much more difficult since the defender's king can block both pawns, as Marshall continued to do here with 58.Kb2.

Rubinstein saw that a pass move such as 58...Rb8 would allow 59.Rh4+ c4 60.Rh7! and black cannot make progress. So, he played the natural 58...a3+? 59.Ka2 Ka4, shielding his king (60.Rh4+ Rb4).

But Marshall found an active but effective policy: 60.Rc1! Ra5 61.Rb1!! after which black was stopped. The Pole tried 61...c4 62.Rb8 Rc5 63.Ra8+ Kb4 64.Rxa3 and conceded the draw after 64...c3 65.Rb3+ Kc4 66.Rb8!.

The subsequent analysis - seeking to find the forced win that virtually all fellow masters felt must be there - led to the discovery of an intricate variation that begins (after 58.Kb2) with 58...Ka5+!. Then on 59.Ka2 black can push the c-pawn: 59...c4 60.Rh8 c3 61.Rc8 Kb4 and 62...Rc5, or 61.Ka3 Rc5 62.Rh1 Kb5 63.Rg1 Rd5! 64.Rh1 Kc4 65.Rg1 Rd2 66.Rh1 c2 67.Kb2 a3+ 68.Kc1 Rd1+ 69.Rxd1 cxd1(Q)+ 70.Kxd1 a2 and wins.

On the other hand, if 59.Kc3, then black wins with 59...a3! 60.Rh8 Ka4 61.Ra8+ Ra5 or 61.Rh4+ Rb4 62.Rh8 Rb3+! 63.Kc2 Rb5 64.Ra8+ Kb4! 65.Rh8 c4 66.Rg8 Ra5 etc.