Brees is day-to-day, Payton reported. The Saints return to practice on Monday after an off day.
The 35-year-old reportedly suffered the injury during Friday's practice.
"In the a.m. practice yesterday, he strained his left oblique. So we'll take it day to day. But we didn't put him out there the day after," Payton said. "So that's gonna require just a little bit of rest. We'll see how it is coming back on Monday and kind of treat it day to day."
The 13-year veteran has missed only one game in his eight-year tenure with the Saints. He is 39 touchdowns away from 400 for his career.
- Chris Mascaro