IF you don’t put away your opponent by move 35, you may be playing at move 125.

This was the moral of the third round of the super-tournament at Morelia, Mexico, earlier this month, when world chess federation champion Veselin Topalov outplayed Levon Aronian during the first two hours.

But when the opportunity for a knockout came at move 34 and again at 35, Topalov of Bulgarian missed his chances. Aronian sacrificed the Exchange and began a counterattack.

Then it was Topalov’s turn to sweat. To stave off defeat, he had to find an inspired defense at move 57.

It soon became apparent this was going to become a marathon, one of those 100-plus-move monsters that every player dreads.

Aronian slowly advanced his remaining pawns, shepherded by a knight and his king. Finally, at move 123, he conceded the pawns couldn’t go any farther and he accepted a draw.

This is hardly a record – even for this year. Nigel Short tried to win R+B-vs.-R until move 124 six weeks ago in Gibraltar.

And there were more than 30 longer games than this in 2005 – including a 150-mover and a 155-mover played by Topalov’s second, Ivan Cheparinov, in the same tournament.