Before the Internet and laptop computers and chess databases, players who wanted to keep abreast of developments in the opening phase of the game had to rely on magazines and books. They were published weeks or even months after important games, so the information was often out of date.

Today’s top competitors have a wealth of up-to-the-minute information, particularly about games of other elite players. So they should be prepared for every match.

But that’s not necessarily the case.

At the rapid tournament in León, Spain, which ended last weekend, Wang Yue of China was leading Magnus Carlsen of Norway in a semifinal match. All he had to do was to draw the last regulation game to advance.