On the final play of the first quarter of the Niners' 24-20 loss to Arizona on Sunday, Williams threw a bone-jarring pancake block on Cardinals linebacker Jordan Hicks that almost immediately went viral.
"I think that's one of the best ones I've probably had, probably put on tape," Williams said. "I've had some good shots where I'm out on the screen and kind of catch a little guy, but in the box it's a lot harder to get those type of blocks. So, I think it would probably rank at the top of my career."
On the play, a 9-yard handoff to tight end George Kittle, Williams said his first job was to read the defense based on if there was a defender lined up over the guard. Williams said with nobody lined up over the guard, he immediately knew that he would have a free run at Hicks.
With Hicks distracted by the 49ers' pre-snap motion and keying on other players, he never saw the 6-foot-5, 320-pound Williams coming.
"I knew I would have pretty much a kill shot on him," Williams said of Hicks, who is 6-1, 236. "I just knew I had to get there pretty quick because if you wait on him, he'll make you miss, they're a lot smaller. I just wanted to kind of get to the second level as fast as I can and take away the option to go either way and just kind of, for lack of a better expression, just kind of lay him out."
The block provided a quick reminder to the 49ers, Cardinals and the rest of the NFL world as to why Williams is a seven-time Pro Bowler and widely regarded as one of the league's best tackles.
Williams said Niners coach Kyle Shanahan sent him a video of the block with a message reading, "Wow, it's good to have you back" on Sunday night. The play was also shown in a team meeting this week, drawing plenty of oohs and aahs from teammates and the coaching staff, though Williams is quick to note that it was far less gratifying coming after a loss.
"I think we all saw it," defensive coordinator Robert Saleh said. "I don't know many human beings his size who can do something like that to a linebacker, nonetheless. Usually you see those guys rolling out on DBs, not a linebacker. No hesitation, run through another human being like he wasn't even there. It was awesome."
For as satisfying as the block was, Williams said he was just happy to be back playing football after such a long layoff. The 49ers acquired Williams, 32, on the third day of this year's NFL draft in a trade with the Washington Football Team for a fifth-round choice this year and a third-round pick next year.
That deal came after a tumultuous year-and-a-half standoff with Washington management over the handling of his injury issues as well as his contract. Before Sunday, Williams had not appeared in a regular-season game since Dec. 30, 2018.
As the Niners and Cardinals warmed up, Williams said players and coaches from both teams made it a point to welcome him back.
"It felt great being back out there," Williams said. "I waited for it for a long time. At one point, it felt too good to be true. But once that ball kicked off, it was like I was back at home, back where I'm supposed to be."
To his teammates, Williams also looked right at home. Matched up often against star Cardinals pass-rusher Chandler Jones, Williams had little trouble protecting quarterback Jimmy Garoppolo's blind side.
To defensive end Nick Bosa, Williams' success against Jones stood out even more than the block on Hicks.
"I think that [block is] super impressive and that's something that not many tackles do but I'm more impressed with how he held up against Chandler Jones the entire game," Bosa said. "He made Chandler look like an average dude out there which is almost impossible to do, and for him to do that first game back, that's pretty unbelievable. It's really cool to have somebody who is the best at what they do -- bar none No. 1 best at what they do -- on your team and I watch him every day and I'm just happy he's on my team."