Lleyton Hewitt has described changes to the Davis Cup as "ridiculous" in a scathing critique of Gerard Pique following his company's link-up with the competition.

A 25-year partnership signed between Barcelona defender Pique's company Kosmos and the International Tennis Federation (ITF) has seen significant alterations to the tournament's schedule.

The 2019 features a solitary Finals tournament involving 18 teams held over one week in Madrid in November.

Last year's four semi-finalists and two wild card teams - Great Britain and Argentina - are already sure of a place in the finals, but Australia must beat Bosnia-Herzegovina in one of 12 qualifiers this weekend to seal their spot in Madrid.

Those changes, and the removal of five-set matches in favour of three-set affairs, have angered Hewitt, who took aim at Pique.

"It's ridiculous," he said of the changes. "He [Pique] knows nothing about tennis. It'd be like me asking to change things for the Champions League."

"The two biggest points of difference were, one, the home and away aspect of it, and secondly was the best of five sets."

"If you look at the pinnacle of our sport, which are the four majors, they're best of five sets."

"By us going back really hurts this event and how important it was."

Roger Federer has also been critical and suggested he may now snub the event, and Hewitt believes the removal of home and away ties for the finals will lead to more of the top stars doing the same.

"In terms of structure and format of the finals, I don't agree," he added.

"Having it at one place I think is ridiculous – I don't think many of the top players will play."

"It's not going to work in tennis. They're basically running the ITF and a soccer league is the main sponsor of the Davis Cup."

"It's mind-boggling."