Tennis' four Grand Slam tournaments pledged on Friday to safeguard the Davis Cup, whose future has been thrown into uncertainty by the end of a deal with an investment company.

The International Tennis Federation (ITF) announced this month it was terminating its agreement with Kosmos, the firm owned by former Barcelona footballer Gerard Pique.

It was an abrupt end to a 25-year agreement worth $3 billion which only began in 2019 with a revamped format and a promise to bring "long-term benefits" for the sport.

Under Kosmos, the home-and-away Davis Cup ties played over several weekends throughout the year were scrapped and replaced with just one home-and-away round of ties followed by 18 teams competing in one city for a week-long climax to the season.

The format was modified again last year, when countries competed in a group stage in September, with the top eight going through to the finals.

"The Grand Slam tournaments are united in their support for the Davis Cup competition, recognising its historical significance and important role in growing engagement in our sport around the world," they said in a statement released during the Australian Open.

The Grand Slams said they believed there was "an opportunity to engage in further discussions with the ITF and ATP regarding the future of the Davis Cup competition" with a view to restoring it to "a premier event with an optimal format and place in the calendar that benefits players, fans and the sport overall."

They added: "Protecting the heritage of the sport and safeguarding major teams competitions such as the Davis Cup and Billie Jean King Cup is a priority for the global tennis community and will appropriately get the Grand Slams' full attention."

The ITF said it welcomed the statement from the Grand Slams. "We look forward to leading further positive conversations with the Grand Slam Board and the ATP," it added.

The ITF has said the 2023 Davis Cup final 8 will take place in Malaga, Spain, in November as planned.