Is it Possible to use a column from a lookup to POST in API?

I am posting a new entry into an object. One of the columns is a lookup table ("UsrCountry") - I know I can post to "UsrCountryId" with the Guid of the Country, but I want to post using the Name (i.e "UsrCounty.Name")

Is this possible to do directly, or do I first need to make a GET call to the "UsrCountry" table to find the ID of the Country Name

Any help much appreciated! I'm posting my collection below

"UsrName": "Test Name", 
"UsrCountry": "Germany",
"UsrExpRating": "5",
"UsrExpRating": "5", 
}