1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 Nc6 Unusual but whether Leonard knows much about it or just played it to avoid Alphaeus's "book" I don't know.
5.Nf3 d6 6.a3 Bxc3+ 7.Qxc3 0-0 8.Bg5 h6 9.Bxf6 Qxf6 10.b4 e5 11.d5 [Maintaining the tension with 11.e3 may have been slightly better but Black can be happy with his opening choices.]
11...Nd4 12.e4 [12.Rd1 ]
12...Bg4 13.Nxd4 exd4 14.Qd3 c6 [14...a5!? attempts to take advantage of Black's development advantage. The same idea was also playable two moves earlier.]
15.f3 cxd5 16.cxd5 Bd7 17.Rd1 Ba4 18.Rd2 Rac8 19.Qxd4 Rc1+ 20.Kf2 Qxd4+ 21.Rxd4 Rfc8 22.Rd2 Ra1 A major transformation. The black rooks are very active and his bishop is better. White sort of hasn't got out of his opening yet! So the missing black pawn matters little.
23.Rg1 Rcc1 24.f4 Kf8 25.e5 Ke7 26.g3 a6 27.Rb2 Bb5 28.Bxb5 Rxg1 29.Be2 Rgb1 30.Rd2 Rxa3 31.Rc2 Rxb4 32.Rc7+ Kd8 33.Rxf7 Diagram
33...Re4 [33...dxe5 34.fxe5 Re4 was better when the white central pawn duo is falling.]
34.Bg4 With the pawn still on f4 this is possible and White suddenly has genuine counterplay and Black can no longer just coast to a win.
34...dxe5 [34...Rc4!? ]
35.d6! There are several tempting rook moves on the 7th rank but the text move is the only one to hold!
35...exf4 Absolutely the only move to hold!
36.Rf8+ Re8 37.Rf7 Ra2+ 38.Kf1 h5 39.Bh3 Rxh2 40.Rd7+ Kc8 41.Re7+ Rxh3?? [41...Kd8 42.Rd7+ with repetition was how the game might have been expected to end.]