Already nursing a left foot strain that kept him out of last week's game, Williams was rolled up on while blocking on a run play. Williams was engaged with a defensive back when Justin Forsett fell into Williams' legs.
Seattle coach Pete Carroll said after the game that the ankle sprain isn't believed to be serious and his previous foot strain was not affected. Williams wasn't in the locker room afterward, but posted on Twitter: "I don't expect to miss the 49er game."
Seattle plays at San Francisco next Sunday.
Obomanu suffered a severe laceration that required a number of stitches to close up. He did not break any bones, but had his right hand heavily wrapped in the locker room.
Obomanu also expects to play next week against the 49ers.
"It was just a good hit in a good place and I think we all get cut, it was just one of those things where he got me pretty good," Obomanu said. "I didn't look at it, but it was pretty bad. We just had to come in and make sure they do what's best for me so I can get back on the field."