Dominic Thiem reaches his first Nitto ATP Finals title match on Saturday at The O2 in London.

Alexander Zverev falls to Dominic Thiem in the semi-finals of the Nitto ATP Finals.

The London 2019 class of ATP University completed their three-day course at the Marriott County Hall.

Dominic Thiem and Stefanos Tsitsipas will battle in the championship match of the Nitto ATP Finals on Sunday.

Dominic Thiem saves all four break points he faces to beat defending champion Alexander Zverev at the Nitto ATP Finals on Saturday.

Alexander Zverev ends his 2019 season with one title and a 44-25 record.

Dominic Thiem owns a 5-1 record in finals this year.

Alexander Zverev and Dominic Thiem have contested eight FedEx ATP Head2Head encounters, with Thiem leading 6-2.

Holger Vitus Nodskov Rune served as a hitting partner for the elite players competing in the Nitto ATP Finals.

Tomas Berdych and his wife, Ester, were on hand for his retirement ceremony at the Nitto ATP Finals.

Dominic Thiem is appearing in his first Nitto ATP Finals semi-final in four appearances.

Recently retired [L to R:] Tomas Berdych, David Ferrer, Victor Estrella Burgos, Radek Stepanek, Max Mirnyi, Marcin Matkowski, Nicolas Almagro, Mikhail Youzhny and Marcos Baghdatis took part in an on-court ceremony at the Nitto ATP Finals on Saturday.

Nicolas Mahut and Pierre-Hugues Herbert own a 2-0 team record in finals this year.

Marcelo Melo and Lukasz Kubot end 2019 with a 46-22 team record.

Alexander Zverev is going for back-to-back Nitto ATP Finals titles in London.

Tomas Berdych finished runner-up at 2010 Wimbledon.

Tomas Berdych wins the 2005 Rolex Paris Masters.

Dominic Thiem is making his fourth consecutive appearance at the Nitto ATP Finals in London.

Tomas Berdych was honored for his career during a retirement ceremony at the Nitto ATP Finals.

Greek Prime Minister Kyriakos Mitsotakis and Stefanos Tsitsipas celebrate Tsitsipas' victory against Roger Federer in the semi-finals of the Nitto ATP Finals.

Nicolas Mahut and Pierre-Hugues Herbert are aiming to become the first French team since 2005 to lift the Nitto ATP Finals trophy.

Nicolas Mahut and Pierre-Hugues Herbert are aiming to become the first French team to lift the Nitto ATP Finals trophy since 2005.

Stefanos Tsitsipas defeats Roger Federer for the second time this year, saving 11 of the 12 break points he faced.

Roger Federer finishes 2019 with a 54-9 record.

The Nitto ATP Finals hosts an on-court presentation to thank players for their many years of service on the ATP Tour.