Next Gen ATP Finals, the tournament for the world’s top players aged under 21 starts in Milan on Tuesday with new innovations that are being tested.

Here AFP Sports looks at those innovations which are being trialled to “add drama, eliminate downtime and increase the pace of play in each match”.

Format

Like the following week’s ATP World Tour Finals in London, the tournament will feature two groups of four with round-robin action followed by semi-finals and the final on Saturday.

- No line judges. All lines called using Hawk-Eye Live

- Best of five sets, but first to four games in each set

- Tie break at three-games all

- Sudden-death deuce points (no advantages). On the sudden death point, the returner chooses which side the server serves from

- No service lets – play continues as it would if there was a mid-point let

- Each match starts five minutes from entry of second player onto court

- A shot clock ensures 25-second rule between points

- A maximum of one medical timeout per player per match

- Coach may communicate with player via headsets in between each set

- Fans will be allowed to move around during a match (except at baselines)

- Singles-only court – no double lines on court to enhance the visual effect in the venue and on TV.

Players

Andrey Rublev, Russia

Karen Khachanov, Russia

Borna Coric, Croatia

Denis Shapovalov, Canada

Hyeon Chung, Korea

Jared Donaldson, USA

Daniil Medvedev, Russia

Gianluigi Quinzi, Italy