Sportal.co.nz 21.Sep.2013Getty Images
The 28-man Wallabies squad will assemble in Sydney on Saturday before flying to Cape Town on Monday ahead of next Saturday's return clash against South Africa.
Horwill sat out the past two Tests against the Springboks and Argentina with a hamstring injury but has been named to lead the touring party and McKenzie is confident the 28-year-old will be on the plane on Monday morning.
"All the reports I'm getting are that he's training pretty well and he's ticking all the boxes on all the things he needs to do, so with a few days to go we expect him to be 100 percent on Saturday," McKenzie said at ARU headquarters.
"He's been working on his rehab in Queensland. Ultimately we'll see what happens when he gets into full-on training on Saturday but he'll be doing contact before that so we'll know pretty well where he's up to."
McKenzie hasn't named a back-up player for Horwill and says the skipper will have to be available for both games of the tour in order to get the nod.
The coach praised Ben Mowen's performance as stand-in skipper in Saturday's 14-13 victory over the Pumas but confirmed Horwill will retain the leadership duties if fit.
Meanwhile, McKenzie challenged recalled loosehead prop Benn Robinson to make the most of his opportunity after replacing Brumbies young gun Scott Sio in the squad.
The 59-Test veteran was a controversial omission from the first four Tests of McKenzie's reign.
"He's a very good scrummager but he hasn't scrummed under these new laws," he said.
"It'll be a Test but at this point in time with a difficult trip we want to back up a win in Perth so we've actually gone for a few more experienced guys who won't be overawed by the occasion or the opposition, but ultimately they have to deliver on the field.
"It's an opportunity for him, he hasn't been in the last period of time so he's got to make the most of it."
The coach confirmed Quade Cooper copped a knock to his leg against the Pumas but declared the mercurial first five-eighths fit to tour.
"He took a bump on his leg on the weekend so he came off with 20 to go but he's fit as anyone else," McKenzie said.
With regards to Cooper's form in his first two Tests back in the number 10 jumper since his 12-month exile under former coach Robbie Deans, McKenzie added: "I think he's going alright. I don't think you can judge on the weekend because we controlled the game from nine a fair bit so there was less to do in that sense.
"Everyone worries about Quade all the time but I worry about the total squad.
"He's contributing as well as everyone else is. Everyone in the squad can be doing things better but I don't sit there and worry about Quade any more than I worry about anyone else."