1.d4
Nf6
2.c4
e6
3.Nf3
d5
4.g3
dxc4
5.Bg2
Bb4+
This Bishop normally belongs on e7 in the Catalan
6.Bd2
a5
7.Qc2
Bxd2+
8.Qxd2
I would have played 8.Nbxd2 to develop the Knight and attack the c4 pawn, and also keeping the Queen attacking that square.
8...c6
9.a4
b5
?! What a strange move for a Grandmaster. Many a club player has fallen from trying to hold onto the c4 pawn. Here it is even worse, with the tactic 10.axb5 cxb5 11.Qg5 hitting g7 and b5, with the Rook on a8 in dire straits as well from discovered attack on the diagonal. The Black side of such positions should go with his gut, and resist the temptation.
10.Na3
Not as forceful as 10.axb5. Was Vishy surprised by 9...b5?!
10...Bd7
11.Ne5
Nd5
12.e4
Nb4
13.0-0
0-0
14.Rfd1
Be8
15.d5
Now all becomes clear. The White position looks far stronger than my suggestion above. All his pieces are developed and his pawns are attacking Blacks weaknesses. In comparison Black has one active piece, the Knight on b4, and it will be a long time before the bad Bishop on e8 unravels itself to free the Rook stuck on f8. The Knight on b8 is usually slow to develop in this type of defensive position. The Rook on a8 really needs to get off that diagonal fast. His pawns will crumble, with the c6 pawn going first.
15...Qd6
16.Ng4
16.f4 with a pawn roller may be better, and the Black Queen may get embarrassed, sitting in front of them.
16...Qc5
17.Ne3
N8a6
18.dxc6
bxa4
Well, Blacks pawns were going to be shattered anyway.
19.Naxc4
Bxc6
20.Rac1
h6
? What about getting that Rook off that diagonal?
21.Nd6
Qa7
22.Ng4
Rad8
23.Nxh6+
! Don't create weaknesses when you don't have to. This underlines what a serious mistake 20...h6? was. Remember, there is no dark squared Bishop to defend, as that was exchanged long ago.
23...gxh6
24.Qxh6
f6
Threat was 25.e5 and sneaking a Rook over the Kingside with Rc4.
25.e5
Bxg2
26.exf6
! Threat is 27.Qg6+ Kg8 28.Rc4. Black is now gone for all money.
26...Rxd6
27.Rxd6
Be4
28.Rxe6
Nd3
29.Rc2
! Pausing to stop any nonsense.
29...Qh7
30.f7+
! Or 30.Qg5+! Kh8 31.Rxe4 as Black cannot play 31...Qxe4?? due to the Mate threat on g7.
30...Qxf7
31.Rxe4
Qf5
Or 31...Nxf2 32.Rf4
32.Re7
! Very cunning. 32...Rf7 33.Rc8+!! Qxc8 34.Qg6+ Kh8 35.Qh5+! Kg8 36.Qxf7+ Kh8 37.Qg7 Mate. 1-0