The Nets are adding former NBA champion Markieff Morris.

Once Kevin Durant rescinding his trade request broke the Nets’ inertia, talks between the team and the veteran power forward accelerated quickly, going from “mutual interest” last week to a one-year standard contract.

The news was first reported by The Athletic, and confirmed by The Post. The deal is non-guaranteed, much like the one the Nets gave Yuta Watanabe. Despite reports that Watanabe got just an Exhibit 10 deal, The Post has confirmed he has a standard contract.

The Nets now have four of their maximum 20 training camp spots left open: All three Exhibit 10 deals, as well as one of their two-way contracts (undrafted rookie Alondes Williams got the other). Restricted free agent David Duke Jr. had initially rejected their two-way offer in hopes of landing a standard deal, but the signing of Morris to the final standard spot ended that possibility.

After adding size on the wings — an Achilles’ heel mercilessly exposed in their first-round sweep by the Celtics — Nets general manager Sean Marks has been looking for a backup big man. At 6-foot-9, 245-pounds, Morris is a rugged, experienced reserve, and a veteran voice in the locker room.

The twin brother of Clippers big man Marcus — both of whom went to APEX Academy in Pennsauken (N.J.) — Morris averaged 7.6 points in 17.5 minutes last season for Miami, limited to just 17 games by injury.

He’s averaged 10.9 points and 5.2 rebounds in his 12-year career, which included winning an NBA title in 2020 with the Lakers.

Morris — who turns 33 on Friday — has been a power forward his entire career, but with added size, declining mobility and a career .341 percentage from deep, he could be deployed at times as a small-ball stretch-5 and backup to presumptive starter Nic Claxton.