Pace bowler Watson, whose presence gives Australia a genuine fifth option in their attack, sustained a calf strain while bowling against Bangladesh in Antigua on March 31 and has missed his side's last two matches.
Ponting said the Queenslander wouldn't be fit for Monday's match here against Sri Lanka, who like Australia have already qualified for the semi-finals, but that he hoped to have him available against fellow last four side New Zealand.
"He won't play tomorrow," Ponting told reporters. "He ran Saturday at about 70 percent.
"He's had a really good hit today (Sunday), he's moving very freely in the nets and I think he is on track as planned to hopefully come back for New Zealand."
Australia have James Hopes on standby for Watson, whose future participation in the tournament would be called into question if he didn't feature against the Black Caps.
"That's something we are going to have to speak about. All the indications are he is going to be right for Friday's game," said Ponting, captain of an Australia side that hasn't lost a World Cup match since 1999.
"If he's not, I know the selectors feel they would like to see him play a game before they'd consider him playing in the semi. But being here, I think we can monitor him pretty closely in his training.
"If he doesn't, for some reason, come up for Friday, then we just have to make sure if we think he's going to play in a semi that we push him as hard as we can in every training session leading into that game to know he's 100 percent right."
Watson, who has played just three Tests, has seen his international career blighted by fitness problems.
The 25-year-old injured his shoulder in his third Test appearance in Brisbane in November 2005 against West Indies.
The all-rounder made his one-day debut international debut in 2002 but his 62-game career in the shorter format has also been interrupted by injuries.
Chosen for the 2003 World Cup squad, he withdrew because of a back problem and had to pull out of Australia's one-day squad that toured Bangladesh 12 months ago because of a right calf strain sustained while making 201 in the domestic Pura Cup final.
He then missed the whole of Australia's recent 5-0 Ashes hammering of England with a hamstring strain.
His place for the past two matches has been taken by batsman Brad Hodge.
During Australia's seven-wicket Super Eights win against England in Antigua on April 8, Andrew Symonds and Michael Clarke saw their combined 10 overs cost 67 runs.
Sri Lanka also have fitness problems with strike bowler Lasith Malinga set to miss his second match of the tournament Monday with left ankle ligament damage.
But without him Sri Lanka still beat New Zealand by six wickets thanks mainly to three-wicket hauls each from left-arm quick Chaminda Vaas and off-spinner Muttiah Muralitharan, two of the stars of their 1996 World Cup winning team.
"Vaas is a class player as well and has been a great bowler for them for a long time," said Ponting.
"What they have done, both Malinga and Vaas, throughout this tournament is take early wickets. They've had opposition teams a couple down early on and that makes Murali more effective through the middle of the innings.
"Our plan will be to get through the new ball as well as we can and keep wickets in hand for the middle part of the game when they slow things down with their spinners, Murali, (Sanath) Jayasuriya and (Tillakaratne) Dilshan."