Please correct/verify if I am using this sentence grammatically wrong.

I wrote an email to all team members. The conclusion of the email ended with a command to tell everyone to win:

"Lets win all games this week."

Because there is a hidden subject "everyone", the sentence is correct:

"[Everyone] Lets win two games this week."

A good friend told me the sentence should be "Let's win all games this week." I understand her point let's is a contraction of let us. Thus, the sentence is "Let us win all games this week."

Here are my questions:

  1. Is there anything wrong with a sentence, "Lets win all games this week."?
    I found many criticisms using "lets" on the web.
  2. If question 1 is correct, which is more appropriated to use in the context above?

The way I understand these two sentences are different.

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Comments  (Page 2) 
"he lets me do something"
"Let's do something"

The two words imply different things. "lets" is a word meaning someone allows you to do something on a regular basis.
"Let's" shows you suggesting something.
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 actually a let is also a noun: in the context of tennis, and also property!
How about this?

Let's make sure she lets us get two lets when we play tennis!
>>>>>So there is no such word as "lets". It is always "let's", which you correctly noted is the contracted form of "let us".

This is not true. She lets us borrow her bike all the time. ok

John let me in yesterday when you were out...ok

Let's plan a party for this weekend! ok
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 anonymous's reply was promoted to an answer.
I don't think the question is about a plural, but about adding an 's' in the third person singular of the present simple...
John lets his children watch TV.
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 anonymous's reply was promoted to an answer.
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