27 Qfh6-f6!! Black f8-rook must protect the g8-mating square J Werle vs P K Wells, 2008  (D39) Queen's Gambit Declined, Ragozin, Vienna Variation, 27 moves, 1-0 Y Erturan vs Potkin, 2001  (C01) French, Exchange, 36 moves, 0-1 2 games