A recent New York Times article about procrastination begins with an etymology lesson:
Etymologically, “procrastination” is derived from the Latin verb procrastinare — to put off until tomorrow. But it’s more than just voluntarily delaying. Procrastination is also derived from the ancient Greek word akrasia — doing something against our better judgment.
The first part is obvious, but the second part struck me as odd, since I'm not aware of any etymological link between the Latin cras ("tomorrow") and Greek κρατέω, krateō, from which akrasia derives.
Is this a valid etymology? If not, is it a common folk etymology, or just a one-off false claim by the article?