Preserve order of classes in a package in testng execution

I have a package with 2 classes.

My testng.xml looks like this:

<test name="Tests">
 <packages>
   <package name="PackageName"/>
 <packages>
</test>

Class2 always runs first followed by Class1.

I want to run Class1 first followed by Class2. Is this possible from this package level configuration?

Thanks, your answers and pointers are appreciative.