Talks fell apart between the Greek government and its creditors, and European officials said Athens' bailout program will expire on Tuesday.
Euro zone finance ministers met to try and thrash out a reforms-for-rescue deal for Greece after the country's prime minister threw a curveball of a referendum on the deal late Friday night. During Saturday's meeting, the finance ministers rejected Greece's request for a one-month bailout extension, meaning that Athens could soon face very serious economic issues.
The marathon talks couldn't be more high stakes. The threat of a liquidity crisis sent countless numbers of Greek citizens scrambling to withdraw funds, prompting massive cash shortages at automated teller machines across the Hellenic Republic on Saturday.
More than a third of the country's ATMs ran out of cash, banking sources told Reuters, amid widespread fears Greece would soon be ejected from the 12-nations that use the euro currency.
"It's not a question to see what might happen on Monday. In terms of a crisis (for Greece), the crisis has commenced," Irish Finance Minister Michael Noonan said after the day's second meeting.
Greece is due to pay the International Monetary Fund 1.5 billion euros Monday and without a deal this weekend risks missing that payment. Christine Lagarde, that organization's managing director, sat down with CNBC to discuss the situation (her comments below).
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—The Associated Press and Reuters contributed to this report.