Miami Heat restricted free-agent guard Tyler Johnson has agreed to sign a four-year, $50 million offer sheet with the Brooklyn Nets, league sources told The Vertical.

Once Johnson, 24, signs the offer sheet at the end of the free-agent signing moratorium on Thursday, the Heat will have three days to match the offer and retain Johnson – or let him leave for the Nets.

For Johnson, the contract represents one of the most rapid financial ascensions in recent league history: From an undrafted NBA Development League guard in 2015, to participating in only 68 games over parts of the past two seasons, to a staggering poison-pill contract that guarantees seasons of $18.8 million and $19.6 million in the final two years of the deal.

Johnson’s agents with CAA Sports – Austin Brown and Ty Sullivan – brought him to Chicago over the weekend to meet with several teams, including the Nets.

Johnson made $507,000 in his second NBA season for the Heat in 2015-16. He played 36 games – only starting five – but NBA executives and coaches who scouted him and studied him closely on tape in the D-League and NBA see the potential for a versatile and complete guard.

The Gilbert Arenas provision allows Johnson to make $5.6 million and $5.8 million in the first two years of the deal, but salaries of $18.8 million and $19.6 million in 2018-19 and 2019-20 make the offer sheet more prohibitive for the Heat to match.

For the Nets, they’re trying to complete a free-agent backcourt that includes Jeremy Lin (three years, $36 million) and Johnson.

Johnson had several comparable offer sheets, but the opportunity for playing time in Brooklyn, the chance to play for new coach Kenny Atkinson and under general manager Sean Marks’ evolving new shingle sold him on Brooklyn.

Sacramento, Chicago, Charlotte and New Orleans were among aggressive suitors for Johnson, league sources said.

Johnson was undrafted out of Fresno State in 2014. He missed nearly three months because of shoulder surgery this past season, but returned in the playoffs for Miami.

Miami president Pat Riley is meeting with free agent Kevin Durant in the New York area and working to re-sign All-Star guard Dwyane Wade. The Heat are keeping center Hassan Whiteside on a four-year, $98 million max contract. Years three and four of the Johnson deal could be difficult for Miami to maneuver under its salary-cap structure.

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