How to find a word before matching string

Question

through to stack-overflow questions but didn't get the proper answer. I need a separate Regex for before & after a matching string.

1) Find word After a specific phrase/word (this one working fine)

  var regex = new Regex(@"(?:" + mytext + @"\s)(?<word>\b\S+\b)");

2) Find word Before a specific phrase/word (not working)

 var regex = new Regex(@"(?:\S+\s)?\S*" + mytext  + @"\b\S");

mytext="xyz"

Input="this is abc xyz defg"

output should be like that

1) for first,which is working
xyz defg

2) second, which is not working

abc xyz

Answer 1

Find word After a specific phrase/word

var regex = new Regex(mytext + @"\s\w+");

Find word Before a specific phrase/word

var regex2 = new Regex(@"\w+\s" + mytext);