"The biggest thing is you don't want it to tighten up on you, and I was trying to keep it loose," Williams told the Chronicle. "We have to figure it out tomorrow once we go in and get a better look.
"There is nothing I can really say about it until then."
The extent of the injury won't be known until further tests are conducted Monday, according to the report.
Williams, who finished with one tackle and one quarterback pressure, went down late during the third quarter when teammate Antonio Smith was knocked into his leg by Saints guard Charles Brown. Williams was able to limp off the field and was seen intermittently riding a stationary bike on the sidelines after sustaining the injury. Williams played on and off in the fourth quarter, however, and was spelled often by backup Brooks Reed.