Defending champion Daniil Medvedev triumphed in three sets in his opening round-robin match at the ATP Finals in Turin ©Getty Images

Defending champion Daniil Medvedev battled to a three-set victory in the opening singles match of this year’s Association of Tennis Professionals (ATP) Finals in Turin, Italy.

The Russian lost the first set on a tie-break against Poland’s Hubert Hurkacz, before coming back to take victory and get off to a winning start in the Green Group at the Pala Alpitour.

Medvedev, who has won 23 of his previous 26 matches and won his maiden Grand Slam title when beating world number one Novak Djokovic at the US Open in September, described conditions in Turin as "probably the fastest I’ve ever faced on the ATP Tour."

Medvedev struggled to adjust to conditions and dropped the first set 7-6 to Hurkacz, who is making his debut at the season-ending men’s event.

However, the second seed turned things around winning the next two sets 6-3, 6-4 to clinch victory in exactly two hours, in a contest where he did not face a break point on serve.

In the evening singles match in the Green Group Olympic champion Alexander Zverev of Germany led 7-6, 1-0 against Matteo Berrettini, when the Italian retired injured shortly after receiving treatment for an injury to a stomach muscle.

In the first of the day’s doubles encounters, also in the Green Group, top seeds Nikola Mektić and Mate Pavić of Croatia beat Germany’s Kevin Krawietz and Horia Tecau of Romania 6-4, 6-4.

Elsewhere in the group a thrilling encounter saw Marcel Granollers of Spain and Horacio Zeballos of Argentina beat Croatia’s Ivan Dodig and Filip Polasek of Slovakia 4-6, 7-6, 10-6.

Mektić is the defending doubles champion at this event, but won the title last year playing alongside Wesley Koolhof of the Netherlands.