Conditional Format - Highlight Cell if Not Sunday

[SaraWitch]

Hello peeps.

I have Column R formatted to ddd, dd/dd/dddd. If the date entered is not a Sunday, I want to highlight it red. I have tried CFs:
=ISERROR(FIND("Sun*",$R3)) (Fill red)

And:
Condition 1: =ISBLANK($R3)=TRUE (No format Set)
Condition 2: = ISNUMBER(SEARCH("Sun*",$R3))=FALSE (Fill red)

Both are highlighting all the cells (which are either blank or have a Sunday date (e.g., Sun, 27/06/2021)).

Any help would be appreciated...

Ta muchly!

 

[SaraWitch]

Perfect; thank you, @Fluff!

Can I adapt the data validation formula to also only allow a Sunday depending on same text?

=WEEKDAY($R3)=1

 

[Fluff]

As that is a totally different question, it needs a new thread. Thanks

 

[SaraWitch]

Apologies - will do. Thank you for your help with CF query...

 

[Fluff]

Thanks for that.