Move 3 e6 (white to move)
FEN: rnbqkb1r/pppp1ppp/4pn2/8/2PP4/8/PP2PPPP/RNBQKBNR w KQkq - 0 3
Comment: Topalov has been known to play the hyper-modern openings and a Benko Gambit isn't so unusual for him. Perhaps he thinks he can outplay the younger Radjabov without resorting to any extreme measures.

Move 5 Bb4+ (white to move)
FEN: rnbqk2r/ppp2ppp/4pn2/3p4/1bPP4/5NP1/PP2PP1P/RNBQKB1R w KQkq - 1 5
Comment: In some situations this move is terrific. I think for the Catalan it's unusual and not so well-known. I have seen a couple of games with it, in which Black was successful, but they are rare.

Move 6 Be7 (white to move)
FEN: rnbqk2r/ppp1bppp/4pn2/3p4/2PP4/5NP1/PP1BPP1P/RN1QKB1R w KQkq - 3 6
Comment: After 5. Nc3 it's not so clear Black would've pulled the bishop back. He might have played 5...c6 or 5...O-O and waited to see if the Bb4 would prove to be of any use.

Move 6 Bg2 (black to move)
FEN: rnbqk2r/ppp1bppp/4pn2/3p4/2PP4/5NP1/PP1BPPBP/RN1QK2R b KQkq - 4 6
Comment: Generally, White's plan it to blast through the g2-a8 diagonal and to play on the queen-side. Bd2 is awkward at the moment, but could come into play at either f4 or g5. If Black plans to block the diagonal with ...c7-c6 then White builds-up more slowly in the center and aims for e2-e4 to overwhelm Classically. Black can aim for equalizing trades or aim to use his queen-side pawns to block and chase White's pieces (as perhaps in a QGA Alekhine's Variation) . It isn't so easy for Black to find a fixed target for a counter-offensive.

Move 9 b6 (white to move)
FEN: rnbq1rk1/p3bppp/1pp1pn2/3p4/2PP4/5NP1/PPQBPPBP/RN3RK1 w - - 0 9
Comment: This is the same plan I'd seen before. Black takes his time building up slowly and planning to meet White head-on in the center.

Move 10 Ba6 (white to move)
FEN: rn1q1rk1/p3bppp/bpp1pn2/3p4/2PP1B2/5NP1/PPQ1PPBP/RN3RK1 w - - 2 10
Comment: This Queen's Indian-ish move is new to me. Whether it's the beginning of a new plan or just a short tactical shot before resuming the slower plan isn't clear. It has the benefit of forcing White to wait on Nb1-c3 and resolve the threat to Pc4 first. 10. b3 is probably alright, but with Bf4 the dark squares b2, a3 and c3 will be weaker than usual.

Move 10 Nbd2 (black to move)
FEN: rn1q1rk1/p3bppp/bpp1pn2/3p4/2PP1B2/5NP1/PPQNPPBP/R4RK1 b - - 3 10
Comment: This resupports Pc4 and controls e4, but blocks the d-file, so that Pd4 might be a little weak; it ties-up Nf3 to defending Pd4.

Move 11 Nbd7 (white to move)
FEN: r2q1rk1/p2nbppp/bpp1pn2/3p4/2PP1B2/5NP1/PPQNPPBP/R4RK1 w - - 4 11
Comment: I like this ordinary-looking move. It appears to be simple development, perhaps preparing ...Rc8 or controlling c5 & e5 (which it does) , but it might also be preparing ...Nf6-h5xf4 by avoiding Bf4xNb8. White's position isn't stagnant, but Black's looks plenty robust.

Move 11 Rfd1 (black to move)
FEN: r2q1rk1/p2nbppp/bpp1pn2/3p4/2PP1B2/5NP1/PPQNPPBP/R2R2K1 b - - 5 11
Comment: Black is a lot less likely to play ...dxc4 and ...c6-c5 when there's a rook aligned with Qd8. It also gets off the diagonal with Ba6 to prepare e2-e4.

Move 12 Rc8 (white to move)
FEN: 2rq1rk1/p2nbppp/bpp1pn2/3p4/2PP1B2/5NP1/PPQNPPBP/R2R2K1 w - - 6 12
Comment: according to Fritz7; This might look a little risky as it leaves Ba6 & Pa7 exposed, but it evacuates the g2-a8 diagonal and prepares ...c6-c5. As long as Black has ...Bxc4 and Pe2 is en prise then it's tacticall sound; but just barely.

Move 13 Nh5 (white to move)
FEN: 2rq1rk1/p2nbppp/bpp1p3/3p3n/2PP1B2/5NP1/PPQNPPBP/2RR2K1 w - - 8 13
Comment: Black would like to move Qd8 off the d-file, but Bf4 is a hindrance. It has to go.

Move 13 e4 (black to move)
FEN: 2rq1rk1/p2nbppp/bpp1p3/3p3n/2PPPB2/5NP1/PPQN1PBP/2RR2K1 b - - 0 13
Comment: Fritz7 doesn't like this and switches the evaluation immediately.

Move 14 gxf4 (black to move)
FEN: 2rq1rk1/p2nbppp/bpp1p3/3p4/2PPPP2/5N2/PPQN1PBP/2RR2K1 b - - 0 14
Comment: This Pf4 will provide some central control, but it's sort of weak. Kg1 is also weakened, so Black need only keep a number of pieces to fight with and not too many weak spots and he should be alright. Immediately it appears Black has to break up some White pawns to avoid a big cramp. The question is whether to capture Pc4 or Pe4. Capturing Pe4 makes Kg1 look less safe, but capturing Pc4 makes Black's queen-side play look better.

Move 15 Nf6 (white to move)
FEN: 2rq1rk1/p3bppp/bpp1pn2/3p4/2PPPP2/5N2/PPQN1PBP/2RR2K1 w - - 1 15
Comment: That's a curious choice: delaying the pawn capture decision. I guess he thinks the threat to Pf4 (...Nf6-h5) will cause immediate and serious problems for White.

Move 16 Nh5 (white to move)
FEN: 2rq1rk1/p3bppp/bpp1p3/3pN2n/2PPPP2/8/PPQN1PBP/2RR2K1 w - - 3 16
Comment: Isn't it rather remarkable that Pf4 was so apart from the rest of the White pieces that White just let it go, so he could continue his main offensive plan, not worrying so much about his king's safety because Qd8 can't get to the king-side just yet.

Move 18 b5 (white to move)
FEN: 2rq1rk1/p3bppp/2N1p3/1p1p3n/Q1bPPP2/8/PP1N1PBP/2RR2K1 w - - 0 18
Comment: Bc4 looks very crowded, but there's still d3 and e2 and as long as Pb5 is mobile the bishop might have time to retreat to b5 or a6 and as long as Pe4 remains then there's ...d5xe4 to open up d5 for the bishop. I think it's this kind of open position which gives Black's pieces more mobility and could lead to a serious king-side attack. But, first he must deal with the Nc6 and Qa4. A queen trade when White's knight would be in enemy territory at d8 (after 18. Nxe8 bxa4)  is risky for White to accept.

Move 19 Rxc6 (white to move)
FEN: 3q1rk1/p3bppp/Q1r1p3/1p1p3n/2bPPP2/8/PP1N1PBP/2RR2K1 w - - 0 19
Comment: Cutting the Gordian knot; Black solves the problem immediately and having captured a pawn at c4 he can already claim material equality. Gaining Pf4 and greater mobility for his remaining pieces would seem to give him some initiative too.

Move 22 exd5 (white to move)
FEN: 3q1rk1/p3bppp/2Q5/3p4/2pP1n2/8/PP3PBP/2RR2K1 w - - 0 22
Comment: After this it appears play has to shift toward the king-side. However, Nf4 has to stay in place to keep Pd5 on the board, so there might be time for b2-b3 to continue on the queen-side.

Move 23 Bh4 (white to move)
FEN: 3q1rk1/p4ppp/2Q5/3p4/2pP1n1b/2R5/PP3PBP/3R2K1 w - - 2 23
Comment: This clears the way for ...Qd8-g5 and guards g3 to prevent Rc3-g3, but that rook has already been en prise (...Nf4-e2+) , so it doesn't make as much sense as ...Be7-b4, preventing b2-b3 and threatening to support ...c4-c3. Perhaps what it is really about is ...Nf4-d3 to attack Pf2 and offer White a way to return material that weakens White's back rank.

Move 23 Rg3 (black to move)
FEN: 3q1rk1/p4ppp/2Q5/3p4/2pP1n1b/6R1/PP3PBP/3R2K1 b - - 3 23
Comment: Fritz7 thinks this just allows Black to trade down to a simple ending with all the advantage. A human knows one pawn in a Q+R+pawns ending isn't much.

Move 24 Re8 (white to move)
FEN: 3qr1k1/p4ppp/2Q5/3p4/2pP1n1b/6R1/PP3PBP/3R2K1 w - - 4 24
Comment: Fritz7

Move 25 Re6 (white to move)
FEN: 3q2k1/p4ppp/2Q1r3/3p4/2pP1nRb/8/PP3PBP/3R2K1 w - - 6 25
Comment: Here comes the cavalry!

Move 26 Nxg2 (white to move)
FEN: 3q2k1/p4ppp/4r3/2Qp4/2pP2Rb/8/PP3PnP/3R2K1 w - - 0 26
Comment: according to Fritz7; ending some of the pressure on Pd5 and further overworking White's defenses

Move 26 Rxg2 (black to move)
FEN: 3q2k1/p4ppp/4r3/2Qp4/2pP3b/8/PP3PRP/3R2K1 b - - 0 26
Comment: awkwardly placed for certain, but White has an exchange, so he might feel secure

Move 27 Qa3 (black to move)
FEN: 3q2k1/5ppp/p3r3/3p4/2pP3b/Q7/PP3PRP/3R2K1 b - - 1 27
Comment: more pieces to the king-side

Move 30 Qa3 (white to move)
FEN: 6k1/5p1p/p3r1p1/3p4/2pP3b/qPQ5/P4PRP/3R2K1 w - - 1 30
Comment: Naturally Black would prefer to keep Pc4, to keep the queen-side files closed to White's rooks and to have an offensive threat (to promote the pawn) . Perhaps he even has the idea of ...a6-a5-a4 and ...Re6-b6 to pile-up on Pb3.

Move 30 Qc2 (black to move)
FEN: 6k1/5p1p/p3r1p1/3p4/2pP3b/qP6/P1Q2PRP/3R2K1 b - - 2 30
Comment: For some reason Fritz7 thinks that getting rid of Pc4 changes the position enough, so it's equal.

Move 31 Qe7 (white to move)
FEN: 6k1/4qp1p/p3r1p1/3p4/2pP3b/1P6/P1Q2PRP/3R2K1 w - - 3 31
Comment: threat: ...Re1+ mating!

Move 33 Qd6 (white to move)
FEN: 6k1/5p1p/p2qr1p1/3p4/3P3b/1Q6/P4PRP/3R1K2 w - - 1 33
Comment: This is a most peculiar position; White is ahead materially, but his king's position is weakened and Rg2 is pretty well stuck. I'd say Black has the advantage if I could find a way for him to attack several points at once to completely overload White's defenses. I suppose the obvious it to focus on Pd4 and Pf2 with ...Re6-e4-f4, ...Qd6-f6.

Move 36 Re4 (white to move)
FEN: 6k1/5p1p/p5p1/3p1q2/3Pr2b/3Q4/P4PRP/3R1K2 w - - 7 36
Comment: setting a very neat trap. After 36. f3?? Re1+ 37. Rxe1 Qxd3+ -+

Move 39 Bf6 (white to move)
FEN: 8/5pk1/p4bp1/3p1q1p/3Pr3/1Q6/P4PRP/3R1K2 w - - 2 39
Comment: Fritz7 (finally) ; This combined with ...h7-h5 might indicate Black intends ...h5-h4-h3 to completely disorganize White's king-side defenses.

Move 44 Rf4 (white to move)
FEN: 8/5pk1/5bp1/p2p1q2/3P1r1p/8/P3QPRP/3R2K1 w - - 2 44
Comment: intending ...h3 and perhaps ...Bf6-h4 to break through at f2, ensuring White's king will never be safe

Move 46 a4 (white to move)
FEN: 8/5pk1/5bp1/3p1q2/p2Pr2p/8/P4PRP/3R1Q1K w - - 0 46
Comment: It's wise for Black to spend the time advancing pawns while White is tied up. There could be a simple ending arising out of this and the more advanced pawns are the ones which could promote first. Of course, Black has to keep the pressure on, so White can't just walk over and grab Pa4.

Move 49 Rb4 (white to move)
FEN: 8/5pk1/6p1/3pbq2/pr5p/5P2/P2R2RP/3Q3K w - - 1 49
Comment: The simple threat of ...Rb4-b1 keeps Pd5 on the board!

Move 52 Bf4 (white to move)
FEN: 8/5pk1/6p1/5q2/pr1p1b2/3R1P1p/P4R1P/3Q3K w - - 2 52
Comment: threatening ...Bf4-e3 to chase Rf2 off the 2nd rank or away from the defense of Pf3

Move 53 Rb1+ (white to move)
FEN: 8/5pk1/6p1/5q2/p2p1b2/3R1P1p/P3QR1P/1r5K w - - 4 53
Comment: according to Fritz7

Move 56 d2 (white to move)
FEN: 8/5pk1/6p1/5q2/p4b2/5P1p/P2p1R1P/3Q3K w - - 0 56
Comment: This pawn is worth a piece, but it would've been a little easier to get in position to escort it forward while it was still on d3.

Move 59 Bd4 (white to move)
FEN: 8/5pk1/6p1/8/p2b4/3q1P1p/P2p3P/3Q1R1K w - - 6 59
Comment: White's army is pretty well immobilized and Black just has to find one small breaking point; perhaps just letting White run out of moves. Qd1 can't move because of ...Qd3-e2-g2#.

Move 62 Bf2 (white to move)
FEN: 6k1/5p2/6p1/8/p3qP2/P4R1p/3p1b1P/3Q3K w - - 3 62
Comment: so that ...Qe4-e1+ can't be met by Rf3-f1