Major League Baseball and the MLB Players Association agreed Tuesday on a new posting system that will allow two-way star Shohei Ohtani to leave Japan and sign with an MLB team for the 2018 season, sources confirmed to ESPN.

Sources told ESPN the system used in recent years will remain in place this offseason. A system with some modifications will take effect next offseason.

Details on the new system will be announced upon ratification by all 30 MLB owners.

The agreement was first reported by the New York Post.

MLB and Nippon Professional Baseball had already settled on a new framework to replace the old agreement, which expired earlier this month, and the union's approval was the final obstacle remaining for Ohtani to leave the Nippon Ham Fighters and play in the majors next year. The commissioner's office and the union extended their negotiating deadline by 24 hours after failing to reach agreement by 8 p.m. Monday.

Ohtani, known as Japan's Babe Ruth, is 23 years old and short of the age-25 threshold that would allow him to leave the Fighters as an unencumbered free agent. MLB teams interested in signing him are limited to a minor league contract plus whatever they have available in their international bonus pool.

Shohei Ohtani is one step closer to leaving Japan and signing with an MLB team for the 2018 season. Koji Watanabe/Samurai Japan/Getty Images

According to The Associated Press, the Texas Rangers have the biggest available bonus pool allotment at $3.535 million. They are followed by the New York Yankees ($3.5 million) and Minnesota Twins ($3.245 million).

The Pittsburgh Pirates ($2.27 million), Miami Marlins ($1.74 million) and Seattle Mariners ($1.57 million) are the only other clubs with available bonus pools of more than $1 million.

Under the terms of the new system, the Fighters will receive a $20 million payment for posting Ohtani, even though his signing bonus will fall well short of that amount.

Ohtani, who underwent surgery on his right ankle in October, is 42-15 with a 2.52 ERA and 1.08 WHIP in five seasons with the Fighters. He has a .286/.358/.500 slash line with 48 homers and 166 RBIs over 403 games during that span.

He would have likely signed a deal in excess of nine figures had he waited until his 25th birthday. But he has consistently expressed a desire to test himself against top competition regardless of the financial ramifications.

"I want to go to an environment where I can continue to get better," Ohtani said during a recent news conference in Tokyo. "I felt the same way when I graduated from high school. And it is my strongest reason for wanting to go now."