Athens, Greece ? The worst blackout in more than a decade hit Athens and southern Greece on Monday, leaving millions sweltering and raising concerns about whether the lights will go out at next month’s Olympics.

The government blamed the outage on “mismanagement” of the electricity grid. Still, officials promised the network was ready to handle the Aug. 13-29 Olympics.

But it was yet another hurdle in Athens’ attempt to convince the world it is ready to host well run and safe games. Olympics preparations have come under criticism because of construction delays and concerns over security arrangements to stop terror attacks.

The blackout, which lasted for up to four hours in some areas, knocked out air conditioners as afternoon temperatures soared to 104 degrees.

In one embarrassing moment for the government, Transport Minister Mihalis Liapis was making a test run to showcase a new Olympic rail link from central Athens to the airport — and got stranded en route when the power failed.