Ever since Kyrie Irving left the Cavaliers for the Celtics, both the Celtics and the Cavaliers have a huge rivalry/competition. They are one of the best rivalries in the game of sports globally. Now, they are going to fight it off in a 7 game series for the conference finals. When either teams win, one side will be happy & one side will feel sorrow. Celtics are up (1-0) now and the next game will be May 15, 2018.