RELATED: 49ers face potential wide receiver dilemma for Week 1
"There has been movement on a deal, but there are some minor details that still need to be ironed out with ownership approval," Schultz wrote.
Last week, NFL Network insider Mike Garafolo reported that Aiyuk and the 49ers were close to finalizing a four-year extension. Only some details—possibly regarding guaranteed money in the final year—were holding up the deal.
"It's really close to being done," Garafolo added. "That's why the 49ers have said, 'We're not going to make a move and trade him away because we feel like we could still get this deal done.'"
Aiyuk attended Sunday's preseason game between the 49ers and New Orleans Saints, watching from a luxury box at Levi's Stadium alongside the team's injured players.
Aiyuk is seeking to become one of the NFL's highest-paid wide receivers, while the 49ers are treading carefully, knowing that their salary cap flexibility will be impacted once quarterback Brock Purdy becomes one of the league's top-paid players.