Which team event did Djokovic help Serbia win in 2020?

Djokovic helped Serbia win the ATP Cup in 2020.

The 2020 tournament was the inaugural ATP Cup, a new international men’s team event organized by the ATP. Serbia defeated Spain 2–1 in the final in Sydney, giving the competition its first champions. Djokovic was central to the victory: he beat Rafael Nadal in singles and then partnered Viktor Troicki in the deciding doubles match.

The ATP Cup is easy to mix up with the Davis Cup because both are international team competitions. The Davis Cup is organized by the International Tennis Federation and has a much longer history, while the ATP Cup was an ATP-run event staged at the start of the season. The ATP Cup was later replaced by the United Cup in the tennis calendar.

Serbia’s 2020 triumph was therefore not a Davis Cup victory or a Hopman Cup title. It was the first ATP Cup championship, secured with Djokovic contributing in both singles and doubles.