Tambling injured his ankle at training on Thursday and has been replaced in the side by rookie Matthew Wright, who was elevated to the senior list earlier in the week.
Walker has a sore glute and failed to train on Friday, but coach Neil Craig said he was confident the enigmatic goalkicker would be fit to take on the Power.
"Taylor has some stiffness in the back/buttocks area. We expect him to be okay, but we wanted to give him every opportunity to play in the game," Craig said on Friday.
"We just thought that to get that he would do minimal [training] today and try [and train] tomorrow."
Tambling was one of three players injured at Crows training on Thursday.
Forward Ricky Henderson copped an errant boot to the head, but has been cleared to play on Saturday night, while utility James Sellar was denied an opportunity to return to the team when he suffered a corked thigh.
Veterans Michael Doughty (corked hamstring) and Scott Stevens (illness) missed the session, but like Tambling are expected to be available for selection next week.
Craig was bemused by inaccurate reports suggesting the injuries were a result of a bruising training session.
"Our training session yesterday was as it has been for the whole year, including the NAB Cup and going into games," he said.
"There was nothing unusual about what we did and the way we went about it. It [the injuries to Tambling, Henderson and Sellar] was just bad luck, I suppose."
The number of players on the Crows' injury list grew to 11 on Friday afternoon when defender Jared Petrenko reported soreness in the foot he broke last season. He will have scans on the injury next week.
The club was forced to make four changes for its round-two clash with Fremantle because of injury and has already made three changes ahead of Showdown 30, with Tambling, Stevens and Phil Davis (shoulder) all unavailable.
Wright and defender Luke Thompson will both make their debut against the Power, while midfielder Myke Cook has been recalled for just his 13th game.
Adelaide's defence has been the hardest hit and Craig said the backline was shaping as one of the most inexperienced in the club's 20-year history.
"You'll glean some information from it [the game] and we've got quite a few players, who we're still gathering information on [in terms] of their response to the demands that we've put on them and the positions they're playing in," he said.
"All players want to be recognised as being able to play under the real heat. This game produces that sort of intensity, so we'll get some information about how some of those younger guys handle it as well as some of the more experienced guys."
Port Adelaide also has an injury concern on the eve of Saturday's game, with injury-ravaged forward Robbie Gray nursing a leg complaint.
Katrina Gill covers Adelaide news for afl.com.au. Follow her on Twitter: @AFL_KatrinaGill
