1.e4e52.b4b53.Nh3Nce74.f4exf45.O-ONg66.d3Bf67.Bxf6Nxf68.Nxf4Qe59.Qg3Re810.Nxg6+hxg611.Qxe5Rxe512.Rb3a613.Ra3Bb714.Rc3Ne815.Nb3O-O16.Nc5Bc817.Ra3Nf618.Nxa6Bxa619.Rxa6d520.exd5Nxd521.a3Ne322.Re1Rfe823.Rc6Nxd124.Rxd1R8e725.Rd2g526.h3Rf527.d4Re1+28.Kh2Rff129.Rc3?!...29.Rd3!kept a significant edge:Re2(29...f5The point is that now this fails to30.Rf3, which forces trades under more favorable circumstances, as afterRxf331.gxf3Re2+32.Kg1, Black has not achieved anything. The c7-pawn still falls, and the c2-pawn is protected. It's counter-intuitive that allowing the rook to reach the seventh rank was the only way to keep an advantage. But such is an endgame against Magnus: if the path to an advantage is there at all, it will not be intuitive.)30.Rg3f631.Rxc7with a likely win.29....f5The most active and testing defense.30.Kg3...30.Rf3Rxf331.gxf3Re3is actually activating for Black. It's not the seventh rank, but it does feature two immobilized targets, so it makes sense that this is more active defense than in the line after 29. Rd3!.30....Kh7??30...g6!was the only defensive try:31.Rf2Rg1!With the f5-pawn protected, what else can White play for?32.d5(32.Rxc7Re3+33.Rf3Re2showcases the active idea behind 31. ... Rg1!.)Re733.Rc6Kh7with the point that, if White's c6-rook ever leaves the c-file, ... Re7-e3+ is a real threat. But as long as White's rook is on the c-file, the rook both defends the c-pawn from e7 while eyeing the key e3-square.34.Kf3Ra1=and now White has to start retreating to defend his weaknesses!31.Rf2f4+31...Rg132.Rxf5is why 30. ... g6 was necesary.32.Kf3Rg133.Kg4...Defending the f-pawn came at the cost of allowing White's king to activate. This removes the key defensive ideas of ... Re1-e3+.33....Kh634.Rxc7Re335.Kf5Rge1??Black is lost now.35...g6+was the only testing try36.Kf6(36.Kg4??Rg3#would be unfortunate.)Rge1but White is much better after (and only after)37.Kf7!with the idea of getting out of potential mating nets by eyeing the g8-square, of all places!(37.Rd2??f3allows Black to resume mating threats!)(37.d5Re5!also uses mating threats to force38.g4fxg3with drawing chances abound.)36.Rc6+Kh537.Rg61-0