Watson exacerbated a calf injury on the eve of the first test and watched from the stands as two players, selected since the recent Ashes whitewash of England, played valuable innings in Australia's 281-run win in the first test in Pretoria over the weekend.
Shaun Marsh scored a century in his first test appearance in two years while Alex Doolan came within 11 runs of a debut test ton.
"We'll have to see how Shane's going in the next couple of days. We probably won't have an idea until we get down there and train and see what's happening," said Australia coach Darren Lehmann as the team left for Port Elizabeth on Monday.
"Obviously we'll have to see what the wicket is like; whether we need the extra bowling option.
"You'd like him to bowl. Firstly we've got to get him fit, and then we'll see what happens from there. He's pretty close; he was running on Sunday," he said.
After the test victory on Saturday, captain Michael Clarke said: "Fortunately I'm not a selector but it's a nice problem to have. We'll wait to see what the selectors come up with."