1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.f4 c5 6.Nf3 In round two, Short played dxc5 against Morozevich, and got into all kinds of trouble. Clearly he found no special improvement and goes back to one of the mainlines.
6...Nc6 7.Ne2 Be3 is the most common guest but Ne2 has already been played by Short more than once and it is unlikely Vallejo was unprepared.
7...Be7 8.c3 a5 9.h4 The main caveat of this move is that it assumes White's king is safe in the center without castling, or at the very least will compensate any risk taken by creating threats against Black's king. It is really not clear how this can be true after 0-0 and f6, opening the f-file and undermining the center.
9...0-0 10.Rh3 f6 11.a3 Rf7 12.Be3 Nb6 13.b3 Qf8 14.Qb1 a4 15.dxc5 Bxc5 16.Bxc5 Qxc5 17.b4 Qf8 18.Ned4? Although a mistake, its refutation is a brilliancy that Nigel should be forgiven for missing.
19...e4!! 20.Nce5 Rxf4! The point is that not only is black threatening f1 behind the knight, but the knight on e5 is actually trapped and has nowhere to escape to.
21.Nh2 Qf5 22.Neg4
22...Rxf1+ [The engine say that 22...h5! was stronger, and while there is no doubting their analysis here, the line is really not obvious and one cannot blame Paco for shirking this choice even had he seen much of the idea. With so many possibiities at every move, simplicity was much preferable. 23.Ne3 Qf6 This move is the key as it pressures c3 and h4. The attack on c3 gains time now, but by freeing the c8-h3 diagonal, e5 will hit hard. 24.Qc2 e5 25.g4 Forced since Rg3 is countered by Qxh4. 25...hxg4 26.Rg3 Qxh4 27.Qg2 d4 And the combination of steamroller center with pieces tied up in knots is winning.]
23.Nxf1 Qxg4 24.Ne3 Qg6 25.Kf2 e5 26.Rg3 Qf6+ 27.Kg1 Be6 28.Qe1 Rf8 29.Rd1 Kh8 30.h5 Qh4 This was the point Kh8, to be able to play this and not suffer a fatal discovered check with Rxg7+.
31.c4 d4 32.c5 Nc4 33.Nf1 Qxh5 34.Rc1 e3 35.b5 e4 It is all over needless to say.
36.Qb4 e2 37.Nh2 Qf5 38.Nf3 Qf4 39.Qe1 Qe3+ 0-1