After an MRI revealed the injury, the team said Lopez will be re-evaluated in one week.
Lopez mostly likely will miss contests against the Cleveland Cavaliers on Monday, a road game against the Chicago Bulls on Wednesday, Friday’s game against the Philadelphia 76ers and Saturday’s game against the Charlotte Hornets.
Lopez missed two games earlier this season with a foot injury.
"Is it a concern? Yes, absolutely," Nets forward Kevin Garnett said to Newsday. "One of your best players, it's a concern when he's hurt. We are hoping for the best with that situation."
Brooklyn has gotten off to an 8-10 start this season and are already six games behind the Toronto Raptors in the Atlantic Division. The injury-prone Lopez, who has missed 136 games in the past three seasons, is averaging 16.1 points, 6.2 rebounds and 1.7 blocks this season.
The team also said guard Joe Johnson is probable for Monday’s game after missing Sunday's practice with a stomach virus.
- Scooby Axson