How doI Redirect Homepage of multisite install to subsite homepage with htaccess

Hi,

How would I go about redirecting the homepage of the multisite domain to the domain of one of the subsites without having issues in the control panel of the main multisite install?
Let’s use example.com as the domain used for the multisite install. And sub-example.com as one of the subsites of example.com (I’ve already set-up the mapping plugin successfully).

I am looking to forward just the homepage of example.com to the homepage of sub-example.com without breaking the wordpress admin panel on example.com (I want to make sure accessing example.com/wp-admin/ doesn’t redirect me as well).

Thanks!