Akiba Kiwelowicz Rubinstein (12 December 1882 in Stawiski, Poland – 15 March 1961 in Antwerp, Belgium) was a famous Polish chess Grandmaster at the beginning of the 20th century. He was scheduled to play a match with Emanuel Lasker for the world championship in 1914, but it was cancelled because of the outbreak of World War I. In his youth, he astonished the chess world, defeating many famous players, including Capablanca and Schlechter; however, his later life was plagued by mental illness.
Between 1907 and 1912, Rubinstein established himself as one of the strongest players in the world. In 1907, he won the Karlovy Vary tournament and shared first at St. Petersburg. In 1912 he had a record string of wins, finishing first in five consecutive major tournaments: San Sebastian, Piešťany, Breslau(the German championship), Warsaw and Vilnius (although none of these events included Lasker or Capablanca). Some believe that he was better thanworld champion Emanuel Lasker at this time. Ratings from Chessmetrics support this conclusion, placing him as world No. 1 between mid 1912 and mid 1914. Reuben Fine, on the other hand, believed he was not quite as strong as Lasker, and was also eclipsed by José Raúl Capablanca after 1911.
He was one of the earliest chess players to take the endgame into account when choosing and playing the opening. He was exceptionally talented in the endgame, particularly in rook endings, where he broke new ground in knowledge. Jeremy Silman ranked him as one of the five best endgame players of all time, and a master of rook endgames