Mod_rewrite matching both subdomain and query string

I'm currently mod_rewriting domain.com/a/123/abc to page.php?this=123&that=abc with:

RewriteRule ^a/([^/]+)/([^/]+)/?$ page.php?this开发者_JS百科=$1&that=$2 [L]

Additionally I now want to mod_rewrite a.domain.com/123/abc to page.php?this=123&that=abc

So both a.domain.com/123/abc and domain.com/a/123/abc will redirect to page.php?this=123&that=abc

My problem is matching both the subdomain and the query string. This is what I've been working on but it's still not rewriting properly.

RewriteCond %{HTTP_HOST} ^a\.domain\.com/ [NC]
RewriteCond %{QUERY_STRING} /([^/]+)/([^/]+)/?$ [NC]
RewriteRule ^(.*) /a/$1/$2 [L]

Note that wildcard domains are set up (*.domain.com). It is just the htaccess mod_rewriting that is failing.

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Is it the trailing / on your RewriteCond?

RewriteCond %{HTTP_HOST} ^a\.domain\.com/

Should be

RewriteCond %{HTTP_HOST} ^a\.domain\.com