Olympic chiefs have ruled out cutting ticket prices in an attempt to boost crowds, despite poor attendances over the opening weekend.
Rows of empty seats form a backdrop at the football
Empty stands at a number of venues had led to calls for a ticket giveaway.
"We will not be giving away tickets," said Michalis Zacharatos, chief spokesman for organisers Athoc.
Latest figures from the Games organisers showed that less than 50% of tickets had been sold in 27 out of 54 events on Sunday.
Mr Zacharatos insisted there would also be no discounted tickets sold.
"This is a policy which is fair to those 2.9 million people that have bought tickets so far," he said.
"With two weeks left, we expect to break the three million mark today. That fact is very surprising and encouraging for us.
"There is no doubt that once we get through the preliminaries the stadia will fill. Most of the events are sold out from the quarter-finals onwards."
In the Group B weightlifting finals, just 841 out of 3,510 tickets were sold (24%) and just over 1,700 people bought tickets for the Japan v Italy baseball preliminary (25%).
But Athens 2004 says eight of Sunday's events were completely sold out, including the Italy-Spain waterpolo and the Greece-Australia basketball match.
These figures do not show how many people attended, however.
John Coates, the Australian Olympic Committee president, said he was concerned at the lack of atmosphere at some events - especially rowing, which saw competition suspended due to high winds on Monday.
"Sports like rowing have only just started in Greece so they have a relatively low number of supporters," he said.
"The atmosphere is always a concern if you do not have a large enough crowd. Let's hope the finals will be an improvement."
Fifa president Sepp Blatter added his concerns about crowd numbers.
Only 1,119 fans filled the 28,000-capacity Kattantzoglio Stadium for the football match between Paraguay and Ghana, while other venues have been equally empty.
"I'm surprised there haven't been more people at the games," Blatter said.
"But it's the same at many other events at the Olympics. I saw a rowing event where you could have had time to shake hands with all the spectators."
Athenians are picking and choosing their events, a process that has left some sports such as tennis, archery and softball playing before near deserted stands.
And the backdrop is a stark contrast to four years ago when sports-mad Australians flocked to various venues in Sydney.