Three days ago, David Johnson said he wanted to get a contract extension done with the Cardinals "as fast as possible."

It came to fruition Saturday night.

On the eve of the regular season opener, the two sides agreed to a three-year deal that will keep the star running back in the fold through 2021. Johnson was in the final year of his rookie contract, so he gets financial stability while the Cardinals lock up their top offensive weapon.

According to Adam Schefter, the extension is worth $39 million, with $30 million of it guaranteed. The total value can reach $45 million, per Schefter.

Johnson has proven himself as one of the game's elite talents since arriving on the scene as a third-round pick in 2015. He showed star potential as a rookie and then exploded in 2016, accumulating 1,239 rushing yards, 879 receiving yards and 20 touchdowns.

Johnson suffered a season-ending dislocated wrist in the 2017 opener against the Lions, but is healthy again and ready to remind people of his talent.

"I think everyone has a question mark on me," Johnson said Wednesday. "They don't know how good I'm going to be. I don't know. A lot of people probably overlook what I did in 2016."

The Cardinals' brass certainly knows Johnson's value, as the two sides worked out a deal despite a split opinion league-wide on the worth of running backs. Johnson has suffered knee and wrist injuries in his last two games on the field, but General Manager Steve Keim told Arizona Sports 98.7 FM on Friday that he didn't need Johnson to show he could stay healthy before giving him an extension.

"Not at all," Keim said. "I'm convinced David is the guy we want to keep as a core member of this team."