The Greek government has admitted that it is not sure whether key transport projects for the Athens Olympics in August will be ready in time.
Last week transport minister Michalis Liapis scrapped part of a planned suburban railway due to slow progress.
"No one can doubt the delays, the bad work and the budget overrun," he said.
"Everything is borderline, preparations are at a very crucial stage - this is the truth. It's time for work and we are determined to succeed."
The newly-elected Conservative government is in a race against time to deliver the Games after sweeping to power earlier this month.
And easing traffic in the notoriously congested city is seen as vital if all the events are to go ahead successfully.
The rail plans were scaled down due to deadline concerns, and Liapis urged builders of a new tram line to hurry up.
"All delays in the tram line must be overcome so the project can be delivered safely on time," he said.
The Greek government has also dropped plans to cover the Olympic swimming pool with a roof and cut back on landscaping at the starting point of the marathon route.
The new cabinet still wants to finish the rail stretch that will connect the centre of Athens with its airport, but shelved a project to link the city centre with the port of Piraeus.
Initial plans had involved revamping existing rail lines and building of a new one by May.
The International Olympic Committee (IOC) has repeatedly voiced concerns about delays in the suburban rail construction and the tram line that will link the centre with seaside Olympic venues.
These include the venues for sailing, taekwondo and beach volleyball.
There are less than 150 days to go to the opening ceremony on 13 August, and more than half of the venues are not finished.
The main Olympic stadium is not due to be ready until three weeks before the Games start.