A left hamstring injury has seen the captain sidelined for his team's first two tri-series matches, one of which was a win over the hosts and the other a loss to South Africa in Harare.
Ahead of facing Zimbabwe, Clarke said he was close to a return.
"Batting-wise I'm completely fine, I feel it a little bit batting but not much at all so it doesn't restrict me," he told the Cricket Australia website.
"The hardest thing has been running, so it's a real positive sign that I've been able to get through today [Friday].
"But there's no point getting on the park just to play a game when we've got 13 other guys here that really want to play and are 100 per cent fit.
"So I don't want to do the wrong thing by the team and my team-mates, but if I pull up OK tomorrow then I'm 100 per cent fit to perform."
While Clarke's absence is a blow, Australia's batsmen have stood up.
Aaron Finch (169 runs) is the leading run-scorer in the tri-series and Glenn Maxwell (100) has also performed well.
The bowling failed to stand up in a seven-wicket loss to table-toppers South Africa.
Kane Richardson, James Faulkner, Mitchell Johnson and Mitchell Marsh have failed to deliver in two matches.
The quartet have taken just one wicket each and need to perform better.
Zimbabwe spinner Prosper Utseya took a hat-trick in his team's loss to South Africa.
The tournament hosts need a win if they are to have any chance of reaching the final of the tri-series.
Australia won the opening match by 198 runs and, despite their bowling problems, should still have too much class for Zimbabwe.