Hardesty, expected to vie with Jerome Harrison to be the starting running back, was injured Thursday but surgery was not required, coach Eric Mangini said Saturday after the Browns' first practice of training camp.
"He twisted his knee in drills the other day, so you probably won't see him for a couple weeks," the second-year coach said. "We're taking it real slow, conservative. We'll see where it is at that point [after rehabbing it]."
The 59th player taken in the draft, Hardesty signed a four-year deal this summer and was one of the team's bright spots during early workouts.
Hardesty had knee and ankle problems while at Tennessee, but Mangini said the latest setback was not related to previous injuries.
Harrison, in his sixth year, had three consecutive 100-yard rushing games as the Browns won their last four games to finish 5-11 season last year.
Mangini was asked who would have gotten the first snap at running back Saturday had Hardesty been around.
"I think the best way to look at this is there's not really a depth chart; it's a rep chart," he said. "Jerome would have taken some of the snaps and Montario would have taken some of the snaps."
The only other notable absentee as the Browns went through their paces before a few thousand orange-clad fans was offensive lineman Tony Pashos, who was fighting a cold. The veteran was signed as a free agent.
The team's first-round draft pick, cornerback Joe Haden, meanwhile, has agreed to terms with the Browns, a team source told ESPN NFL Insider Adam Schefter. Contract details were not immediately available, but The Plain Dealer (Cleveland) reported the deal was for five years and $50 million, with $26 million guaranteed.
Information from The Associated Press was used in this report.