String.format() takes an array as a single argument

Why this does work OK?:

String f = "Mi name is %s %s.";
System.out.println(String.format(f, "John", "Connor"));

And this doesnt?:

String f = "Mi name is %s %s.";
System.out.println(String.format(f, (Object)new String[]{"John","Connor"}));

If the method String.format takes a vararg Object?

It compiles OK but when I execute this the String.format() takes the vararg Object as a single an unique argument (the toString() value of the array itself), so it throws a MissingFormatArgumentException because it cannot match with the second string specifier (%s).

How can I make it work? Thanks in advance, any help will be greatly appreciated.