The Barcelona defender, who spearheads the company behind the new format of the Davis Cup, said Wednesday that Nadal has told him he will play as long as he is not injured.
"If the No. 1 in the world is playing, that's more than enough," Pique said in the official presentation of Madrid as host of the Davis Cup finals for the next two years. "Rafa is very positive about this event, especially because it is taking place in Madrid."
The new event was developed in a partnership between the International Tennis Federation and the investment group Kosmos, which was founded by the Barcelona and Spain player.
Pique said he knows it will not be easy to have all top-ranked players participating.
"This is a team event, so it's impossible to have all the top players involved. Some teams won't qualify, not everybody will be able to play anyway," Pique said. "Of course we would like to have the top players, but we want to focus on the teams."
Stars such as Novak Djokovic and Roger Federer have already hinted they don't intend to play. Djokovic said the tournament could be competing with the ATP's World Team Cup, while Federer said the revamped Davis Cup didn't seem to be designed for him.
Pique said he already didn't expect Federer to be playing, noting the Swiss veteran has limited his tournament schedule in recent years and might not "have the legs" to play in the Davis Cup again. He said he still hoped to convince Djokovic, though.
"I have a lot of confidence that we can negotiate and the top players will play," Pique said.
The new format of tennis' top team event will be a season-ending, 18-team tournament, but teams will still play matches in February to advance to the championship in November. The Davis Cup has previously been played over four weekends throughout the year.
The first championship will be held next year from Nov. 18-24 on an indoor hardcourt at the Magic Box arena, which already hosts the Madrid Masters. The ITF said players will compete for prize money that will rival what is offered in Grand Slams.
Pique said there is no "perfect date" for the tournament as the tennis calendar is very tight, but he was happy with the week they picked.
"We've spoken with everybody," he said. "We think this is a week that won't affect any of the other tournaments. We want to be well seen in the tennis world. We are here to help. We think this will be a magical week for the world of tennis."
The 2018 Davis Cup semifinalists — Croatia, France, Spain and the United States — have already secured their spot in next year's tournament, along with Argentina and Britain.
Defending champion France will host Croatia in the last Davis Cup final in the current format from Nov. 23-25 in Lille.