Atop the list of 49ers' offseason priorities sit the prospective contract extensions for tight end George Kittle and defensive tackle DeForest Buckner. Both players are entering the final year of their current contracts and rank among the best talents at their respective positions throughout the entire NFL.

San Francisco selected Buckner with the No. 7 overall pick in the 2016 NFL Draft, and he has served as the keystone of the defensive line ever since. He was a critical part of the 49ers' run to Super Bowl LIV, and the team reportedly tried to lock Buckner down for the foreseeable future before the journey to Miami it even got started.

The Athletic's John Middlekauff reported Monday that San Francisco offered Buckner a lucrative extension last offseason, which he ultimately turned down.

"I was told that last year they made a very aggressive offer to him," Middlekauff said on "The Haberman and Middlekauff Podcast." "We're talking in the $60 million range ... Fletcher Cox, years ago, got $63 [million]. They offered less than that, and he said no."

However, Buckner recently took to Instagram to argue against Middlekauff's report.

"When did we start believing everything on the internet," Buckner commented.

Entering his age-25 season in 2016, Cox signed a six-year contract extension with the Philadelphia Eagles for $63.3 million guaranteed. Buckner will turn 26 in March, and one could argue he was more productive over his first four NFL seasons than Cox was. Yes, Cox forced two more fumbles than Buckner, but the 49ers' standout started six more games, deflected nearly twice as many passes, recovered one more fumble and totaled 6.5 more sacks.

For that reason, combined with inflation and the fact that the salary cap has risen since Cox signed his extension, it wouldn't be surprising if Buckner sought a higher guaranteed total from San Francisco -- and received it. 

[RELATED: 49ers want to bring everyone back, but know it'll be tough]

Whether or not he already has turned down such an offer is anyone's guess. But it shouldn't be long before we find out exactly how much is guaranteed on Buckner's next deal.

One thing is certain: It's going to be a lot.