Case and IF clause in sql server

I need to concate 0 when month and day is less than 10 (Or Single Digit value). When i am using IF statement it works, but in CASE statement it's doing an addition.

IF Statement

IF Month(getdate()) < 10
 Begin 
 select '0' + cast(Month(getdate()) as varchar(10))
 END
Else
BEGIN
  select month(getdate())
END

CASE Statement

SELECT 
CASE
    WHEN(
        CAST(Month(getdate()) as varchar(10)) < 10
    ) THEN '0' + cast(Month(getdate()) as varchar(10))
    ELSE (Month(getdate()))
END