FORT WORTH — The finals of the 14th Van Cliburn competition began as the preliminaries had begun: with the king of music, Beethoven.Specifically, Beatrice Rana of Italy joined Leonard Slatkin and the Fort Worth Symphony Orchestra Thursday evening for Beethoven’s Piano Concerto No. 3 in c minor.Rana has been impressive all the way through this competition, and she easily met expectations in a performance that was full of both power and grace.The long orchestral introduction of the Beethoven gave the audience a chance to size up Slatkin and the Fort Worth Symphony.All seemed satisfactory here as they built up a miniature drama of gathering power and a musical omen of things to come.(In the very first Cliburn, the orchestral introductions were abridged. The competition has come a long way in many respects.)Rana is an aristocrat of the piano.I loved the way she handled the first-movement cadenza.Traditionally this is a place for showing off, but she made it an integral part of the movement, with a smooth transition back into the main body of the work.There was much to like in the subtlety-with-power that characterized the performance throughout.The first gentle notes of Prokofiev’s Piano Concerto No. 2 in g minor are not what you would expect of a virtuoso showpiece, but this was Prokofiev, and Nikita Mndoyants was playing, and you knew there were fireworks to come.Like Rana, Mndoyants has been playing well throughout the competition, and his finals performance Thursday was in line with expectations.There was plenty of fire combined with lyrical grace, and with the backing of Slatkin and the orchestra this became a real tour de force of musical talent and showmanship.Rachmaninoff’s Piano Concerto No. 3 may not have been the best choice for Fei-Fei Dong.There was much to like in her performance, but it seemed that this monumental virtuoso vehicle never quite reached its potential.Dong throttled back in both tempo and tension in both the second and third movements, and the work did not have the exhilarating drive to the finish that characterizes the best performances.The orchestra made some mighty noises Thursday evening.With all three soloists, Slatkin was a sympathetic but strong partner.In Dong’s Rachmaninoff, he insisted on drama, even if the pianist had to be submerged in a few places.