Bottom note box.
Know Your Phrase - Common Idioms and Phrases, Their Meanings and Origins > O-Letter Sayings
The origins of this idiom.
The meaning of this phrase.
Phrases and Idioms
knowyourphrase.com - The Meanings and History For Popular Idioms and Phrases | Use this handy list of phrases to search for more!
O
1. A quick left jab followed by a right hook; an old boxing tactic.
2. A powerful combination of two people or things.
This phrase is believed to have originated from the sport of boxing. The earliest that I could find this phrase was during the early 1900s. For example, in the Oakland Tribune, June 1919, the expression is used within the context of boxing:

"The fans will see a big difference in Frankie. He is far stronger than he was before going to France,
and he is hitting much harder. He has the old one-two punch down to perfection and he stings every
time he lands."

The idiom eventually began to not only refer to a strong combination of punches in boxing, but also to things or people that are considered to be a strong combination. An example of this phrase used outside the context of boxing is seen in the Lowell Sun from 1949, which reads:

"And maybe that's the way the old team of Stalin and Molotov figured in the first place, since they've
been working together for 35 years: The old one-two, with Molotov being tough and Stalin being soft
if he had to."
* Out on the beach, me and my buddy Alice are considered as the one-two punch duo, because we're unstoppable in the game of volleyball!
Note: The origins for most common idioms cannot be said with a certainty. What's provided are theories that may be plausible to how a phrase originated, but not necessarily so.

In addition, quotes that contain a phrase may be taken from old newspapers, poems, or books that were written centuries ago, but this by no means shows they originated from these. In all likelihood, if an expression is being used in a newspaper, it's probably already well known, and thus, from an older period of time.