Following the world finals, the Association of Tennis Professionals (ATP) announced that the Italian Tennis Federation, in association with the Italian Olympic Committee, will organize a new ATP tournament featuring the world's top 21-and-under singles players of the ATP World Tour season. The first five editions of the Tournament will be hosted in Milan from 2019 to 2021. The other new event is a modernized version of the Davis Cup Competition, in which the top 18 tennis-playing countries in the world playoff for one week to determine the champion. The new Davis Cup format: Eighteen nations are split into six groups of three, with the group winners and two best- placed runners-up progressing to the quarter-finals. The two semi-finals will be played on Saturday, November 23rd, with the two winners going through to the final on Sunday, November 24th. The six groups: Group A: France, Serbia, Japan Group B: Croatia, Spain, Russia Group C: Argentina, Germany, Chile Group D: Belgium, Australia, Colombia Group E: Great Britain, Kazakhstan, Netherlands Group F: United States, Italy, Canada Which of the world's top 20 are playing? Rafael Nadal (Spain) [1] Fabio Fognini (Italy) [12] Novak Djokovic (Serbia) [2] Diego Schwartzman (Argentina) [14] Matteo Berrettini (Italy) [8] Denis Shapovalov (Canada) [15] Roberto Bautista Agut (Spain) [9] Karen Khachanov (Russia) [17] Gael Monfils (France) [10] Alex de Minaur (Australia) [18] David Goffin (Belgium) [11] Schedule - who plays when? Group stage: Monday, November 18th - Thursday, November 21st Quarter-finals: Thursday, November 21st - Friday, November 22nd Semi-finals: Saturday, November 23rd Final: Sunday, November 24th .