The former Test skipper said Watson would be putting too much pressure on the team if he went into battle with South Africa still nursing his calf strain.
Watson was put through a fitness test at Adelaide Oval on Tuesday as the allrounder continued to push for a recall to the side as a batsman only.
The 31-year-old completed a number of running exercises but rarely reached anywhere near full steam.
Ponting said Watson was looking good in the nets but was restricted from doing anything else in the field except slips catching.
A decision will be made on Wednesday or the morning of the match, but Test rookie Rob Quiney is tipped to retain his place at No.3.
"It doesn't matter what we think as teammates - he will have a certain lot of criteria he will have to pass. There will be a certain amount of running he will have to do to prove that he's right to play a Test match," Ponting said.
"No one can go into a Test match 70 percent fit.
"I don't care if you're a batsman and a slip fielder.
"If you can't bat at 100 percent, then you are putting pressure on other blokes as well.
"Someone has got to run with him between wickets and I'm sure that will be in the back of his mind and it will certainly be in the back of the mind of our physio and doctors that are looking after him.
"They will make sure they tick all the boxes."
The other contentious spot in the Australian line-up concerns fast bowlers Ben Hilfenhaus and Mitchell Starc, who are vying for the final place in the attack.
Starc said earlier on Tuesday he still didn't know if he was to come in for incumbent Hilfenhaus, but declared he was ready to fire if recalled for what would be his fifth Test.
"If I'm picked, I'm ready to go and do my job for the team," he said.
"I'm happy with how the ball has been coming out the past couple of weeks."