SAN ANTONIO -- Spurs rookie guard Lonnie Walker IV underwent an MRI examination Saturday morning in San Antonio that revealed a right medial meniscus tear, the team announced.

Walker is likely to miss six to eight weeks, a source told ESPN's Adrian Wojnarowski.

He suffered the knee injury at the 6:55 mark of the fourth quarter of Friday's preseason win over the Detroit Pistons.

The Spurs announced Walker will undergo surgery in San Antonio on Monday, with team physician Dr. David Schmidt performing the procedure.

San Antonio plans to announce a timeline for Walker's return at a later date.