The fight between Crawford and Spence is expected to take place in November.
The two superstars have agreed to all material terms for a fight in Las Vegas.
As their lawyers clean up some of the legal language in the agreement, the contract hasn't been signed by Crawford or Spence.
The loser of the fight will have the right to go back in the ring.
The winner will earn most of the revenue for the return bout according to sources.
It will be Crawford's first fight of the year. He defeated Shawn Porter in the 10th round to retain his WBO title.
In April, he returned to the ring and scored a win over Yordenis Ugs with a 10th-round knockout. He won the title of world's lightest weight.
Prior to the bout, he said he wanted to face Crawford.
✨ Watch more top videos, highlights, and B/R original contentIt would only be one belt left, he said. I will be campaigning for that fight.
Due to a broken jaw he sustained during sparring, he was forced to withdraw from the fight against the Filipino.
Crawford and Spence are the top two fighters in the division, according to the website. They have a combined 66 victories by knockout or TKO.
The IBF title has been held by Spence.
After three years as a light welterweight, Crawford moved up to a new weight class in the fall of 2018? In his first fight as a 147-pound, he defeated Jeff Horn.