Joseph Tsai, the billionaire co-founder of Alibaba, is in talks to buy Brooklyn’s Barclays Center and the new Nassau Coliseum in Uniondale from Russian billionaire Mikhail Prokhorov, The Post has learned.

The negotiations are expected to pave the way for Tsai, 55, to become the new owner of the Brooklyn Nets NBA team, sources said.

Tsai, whom Forbes estimates is worth $9.9 billion, is already a minority owner of the Nets after buying a 49 percent stake in the Brooklyn b-ball team from Prokhorov last year for $1 billion.

The deal gives Tsai, who hails from Taiwan, rights to buy the rest of the team before the 2021-22 basketball season for an additional $1.35 billion.

By buying Barclays, it will be easier for Tsai to buy the Nets because the NBA likes its owners to own the arenas where their teams play, sources said.

It also lets Prokhorov, whom Forbes estimates is worth $9.8 billion, sell Tsai his 51 percent stake in the Nets ahead of schedule, a high-ranking sports executive familiar with the talks told The Post.

A sale to Tsai would be embraced by the NBA, which is anxious for him to take control of the Nets so he can help the league grow in China, sources said. Tsai is a member of NBA China, which conducts league business in that country, even though he doesn’t yet control a team.

“The league would be ecstatic,” a source said.

The Nets are currently suffering the worst attendance of the NBA’s 30 teams, at 14,639 a game, even though their game has improved enough that they are poised to make the playoffs for the first time in four years.

The team was not making any money as recently as last year, one sports exec said.

By selling a minority stake to Tsai, Prokhorov immediately reduced his costs associated with the team. In an agreement signed with the NBA last year, Tsai and Prokhorov agreed to provide the Nets with the extra funding the team needs to meet its expenses and payment obligations, research firm Moody’s Investors Service said in a research note.

A change in ownership could also help shore up the Barclays Center, which opened with a splash in 2012 but which has been struggling to make a profit.

Last June, Moody’s projected Barclays — which cost $1 billion to build and drew rapper Jay-Z as an investor — would break even in 2018.

One of the financial drags on the arena has been the New York Islanders hockey team, which also plays there and which has been suffering from poor attendance and sponsorships.

The Islanders recently moved half their games to the new Nassau Coliseum, which replaced the old one of the same name in 2017. That has Barclays seeking to boost its profits by hosting more concerts, shows and other events, Moody’s said.

Prokhorov is required to provide Barclays with the funding it needs to meet its expenses and payment obligations, according to Moody’s.

A spokesman for Barclays and the Nets disputed this story, declining to give further details.