Henderson was part of a pass breakup along the sideline. After apparently being stepped on, according to head coach Leslie Frazier, Henderson's momentum carried him out of bounds, where he kicked a plastic cooler in frustration and sat on the ground clutching his left heel area.
After getting the heel, ankle and foot area taped, he returned for a few goal line snaps but later left practice to go inside for further evaluation.
"Just to go in and let them take a look at his heel. It got stepped on, but it should be fine (Friday)," Frazier said.
Second-year linebacker Audie Cole took Henderson's place for the remainder of practice.
"I think he is really improved and then having an offseason with us, a full offseason as a veteran, has helped him," Frazier said of Cole. "We have a lot more confidence in him today as a middle linebacker than we did as a year ago about this time as a rookie. He's beginning to show some leadership ability, which you need at the middle linebacker position. So I think he's going to be a capable guy if something were to happen to Erin that we could count on."
The Vikings were also missing starting left guard Charlie Johnson, who was dealing with a family matter. Frazier said he doesn't expect Johnson to be back for Friday's practice but should play Sunday night at San Francisco.
THIN AT D-TACKLE
DT Sharrif Floyd remained out with a knee injury. He had a "minor procedure" performed on the knee earlier this week, but defensive coordinator Alan Williams said Floyd continues to stay involved in the mental aspect of preseason, even if he doesn't play the rest of the way.
"The one thing that Sharrif is doing, he's studying tape, he's paying attention out there on the field, he's listening to the veterans in terms of what they're saying. He's studying at home," Williams said. "He's doing everything that he's supposed to do to get himself back.
"But the one thing that he can't do is just see the live reps. We're just going to have to wait until he can get back on the field to do that. And then once he gets back, he's just going to have to work himself into seeing those blocks that he'll see in the ballgame. We'll see. I do know this, though: When he came in, he didn't play and he didn't practice like a typical rookie. He was a little bit further ahead. When he had a problem, he solved those problems and moved on rather quickly. I expect that he'll be OK, but again, he's still a rookie. We'll just make sure we get up to speed when he does get back on the field."
Christian Ballard, who was a rotational defensive tackle for the Vikings last year, remains on the active/left squad list, and Frazier said there was nothing new concerning his status.
With Floyd and Ballard out for Sunday night's game, it creates a bit of a depth issue for the Vikings.
"We don't want to overwork Kevin (Williams) for sure. Some other guys are going to get some playing time – Chase Baker will be one of them," Frazier said. "… It just means other guys will get more snaps."
Chase Baker, who spent last year on the practice squad, will be one of those players getting elevated reps in San Francisco.
"He's had a good camp. He's done some things to make you take notice," Frazier said. "You want to get good players on the field, so this is a golden opportunity to him."
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.