Sax,Gyula (2565) - Banas,Jan (2390) [C92]
ARTIA op Balataonbereny, 1984
[Llewellyn,Alan]

Gyula Sax is a rather less famous eastern european player who died in 2014. His abilities over the chess board were probably hampered by the fact that the Russians wanted only Soviet Players to shine in these events and he was Hungarian, also his success came later in life in the 1980's when he was in his mid to late 30's. But still he reached the Candidate Matches a couple of times. His opponent was a Yugoslav player who reached International Master level which is just one type of title lower than Grandmaster.

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 d6 8.c3 0-0
This lines are very popular in modern chess, and are called the Closed Ruy Lopez Systems. Note The Karpov Variation with 9...Be6 is very popular.

9.h3 Bb7 10.d4 Re8 11.a4 h6 12.Nbd2 Bf8 13.Bc2 exd4 14.cxd4 Nb4 15.Bb1 bxa4 16.Rxa4 a5 17.Ra3 Ra6 18.Nh2 Qa8?!
[18...Qd7!? 19.Rg3 Qb5!! to stop e5 20.e5?? dxe5 21.Ndf3-+ ]

19.Rae3 Qa7 20.e5 Nfd5 21.Rg3 dxe5 22.dxe5 Rae6 23.Ne4!
the start of an attack against the King.

23...Kh8?! 24.Nf3! Qb6??
[24...Be7+/= this was essential to defend the g5 square, why will be shown in dramatic style in the following moves by Gyula.]

25.Nfg5!! hxg5
[25...R6e7 this Rook move was best but it ends disasterously as well. 26.e6 f5 27.Nf7+ Rxf7 28.exf7 Rxe4 (28...Re7 29.Qh5 fxe4 30.Bxh6 Qxh6 31.Qxh6+ gxh6 32.Rg8+ Kh7 33.Rxe4 Nc3 34.Rxe7+ Nxb1 35.Rxf8 Nd5 36.Rh8+ Kg6 37.f8Q Nxe7 38.Rxh6+ Kg5 39.f4# ) 29.Bxe4 fxe4 30.Rxe4 Qf6 31.Qh5 Kh7 (31...Nf4 32.Bxf4 Bxe4 33.Be5 Qe6 34.Rxg7 Bxg7 35.f8Q+ Qg8 36.Bxg7+ Kh7 37.Qxh6# ) 32.Re8 g6 33.Qg4 Qxf7 34.Rxf8 Qxf8 35.Qxg6+ Kh8 36.Bxh6 Ne7 37.Bg7+ Kg8 38.Qe6+ Qf7 39.Bh6+ Kh7 40.Qxf7+ Kxh6 41.Qg7+ Kh5 42.Qh7# Note-these are computer moves in a complex position almost designed for computer analysis where mere humans commit poor moves, even Grandmasters.]

26.Nxg5 g6
[26...Nf6!! Jan lives on with this move though its questionable he would have wanted more punishment. 27.Be3 Rxe5 28.Nxf7+ Kg8 29.Nxe5 Qd6 ]

27.Qh5+!!
the point being, after the obvious 27...gxh5 then 28.Nxf7 is a rather unusual mate. The Motif is unusual because the Rook on g3 is in a rather unfortunate position for the poor Jan. 1-0