A defender a pawn down can draw by keeping his king in front of the enemy passed pawn and using the blocked pawn pair to build a stalemate.
Grigoriev again (1936), this time with White a pawn down and looking for a draw. White has only c2 against Black's c3 and e6; the kings are on b1 and f6. The c-pawns are frozen, so the real question is whether the black e-pawn can be stopped.