He played carelessly and lost a pawn on move 21.

Qe3 30 fe, Korchnoi had to lose a pawn.

Anand lost a second pawn to 34 Bc6, yet continued until he was bereft of reasonable moves after 65 d5.

There are now several alternatives for Black, with one a clear error, as it loses a pawn: 10...e5 11.

After 30 Re6, Kasparov had to lose a decisive pawn.

Soon, on 19 Qe2, Ribli was going to lose a pawn.

But after 25 Nf7, Ponomariov still had to lose a pawn.

Any move by a black piece loses at least a pawn .

This move looks like an elementary blunder, losing a pawn, but in fact the position is more complicated than that.

He seemed to be drifting, then erred with 17 f6, losing a pawn.