The 1921 World Chess Championship was played between José Raúl Capablanca and Emanuel Lasker. It was played in Capablanca's native Havana from March 18 to April 28. Lasker resigned the title in 1920 in a dispute over match conditions, but agreed to take part as challenger in 1921 (partially due to his having lost a lot of money due to the First World War).
The championship was set to last for 24 games: the first player to accumulate 12½ points (or win eight games) would be World Champion. If it ended 12-12 the incumbent would retain the title. Lasker had won the previous championship, but he resigned it in 1920, meaning that technically he was the challenger and Capablanca the incumbent for this match, even though the two had never met in a title match before.
Lasker resigned the match, making Capablanca the new champion.