The team simply hoped he'd be all right. Fast forward two days and after Sunday's practice Celtics coach Brad Stevens wasn't even willing to rule out the possibility of Walker playing Monday night back here against the Sacramento Kings -- a result Stevens called a "minor miracle."
"Obviously they went through a series of things with the Denver doctors, and a series of things when he got back yesterday with our doctors," Stevens said after the Celtics practiced Sunday. "So he is continuing to be monitored in case any of that stuff shows up.
"But he's been good, and he feels good. It's kind of a minor miracle based on what we saw the other day. But the strain is real, and he's got some soreness in his back and neck. That's it."
Stevens reiterated the team's update from earlier Sunday that Walker was doubtful for Monday's game against the Kings, but said there was a chance Walker, who wasn't available to speak to the media Sunday, could play. Stevens added that Walker didn't practice Sunday, but he did work out on an exercise bike and in the weight room at the team's practice facility.
Stevens said that during his final season at Butler, he had a player go into the stanchion and temporarily lose his ability to move his arms and legs. So, as he saw Walker go down Friday night after running into teammate Semi Ojeleye, he said that moment -- and whether Walker was moving -- was the first thing that came to mind.
"Then I saw him moving a little bit," Stevens said, "but he was clearly, like, balled up ... when they put him on the stretcher, I don't know if he was in shock, or what the deal was, but 10-15 minutes later in the ambulance, he looked totally different.
"But it's scary. It's always scary. And that's the reason he's doubtful [for Monday], to be honest. I think he could probably play with the strain part, but we want to make sure [that] with the way he hit, and certainly because of the sensitivity to head injuries."
Stevens said that Walker, who initially the Celtics said was being treated for concussion-like symptoms Friday night, had not been placed into the league's concussion protocol, as far as he knew.
While Stevens left the door open for Walker to play, Jaylen Brown -- who had his own health scare last year when he fell after a dunk against the Minnesota Timberwolves in March of 2018 and suffered a concussion -- said he'd advise Walker to take a game before he comes back.
"I think that's Kemba's call," Brown said. "There's no rush for him to get back. If he's feeling good, of course [we want him back]. But sometimes [after] things like that, you need to take a breath, take a break, until he's ready to go back into it.
"But it's completely up to him, for sure. If I was him, I would take a day away, and then come back."
Walker is averaging 21.1 points, 4.6 rebounds and 4.7 assists in his first season with the Celtics after spending eight years with Charlotte and then joining Boston as a free agent this summer.
The man Walker replaced at point guard for the Celtics, Kyrie Irving, has already been ruled out for the Brooklyn Nets for Wednesday's game between the two teams in Boston, which was supposed to be his first game there since joining the Nets as a free agent this summer.
Beyond hosting Sacramento and Brooklyn this week, the Celtics play in Brooklyn Friday and at Madison Square Garden against the New York Knicks Sunday.
In other injury news, Celtics forward Gordon Hayward, who had surgery to repair a broken bone in his left (non-shooting) hand on Nov. 11, was shooting after practice without any issues, with only some tape on his fingers on advice from the doctors. The Celtics initially ruled him out for up to six weeks.
"He's great," Stevens said. "Feeling well. He's got some swelling where the incision was, but that's to be expected. He's doing a really good job. It seems like he's on pace."