URL fight between MediaWiki & WordPress

I’m running a MediaWiki installation on domain.com/wiki. If a user enters domain.com he’s forwarded to domain.com/wiki via .htaccess.

Now I want to setup WordPress on the same domain and I want to have my WordPress pages at domain.com/page1 and domain.com/page2.
I managed to have URLs like domain.com/wordpress/page1 and domain.com/wordpress/page2 – but I don’t want a subfolder “wordpress” in my URLs.

I also tried the multi-site feature – but it allows only domain.com/wordpress/multi-site1 and domain.com/wordpress/multi-site2.

Can anyone help me please?
Maybe I have to build a special .htaccess which forwards domain.com to domain.com/wiki and apart from that includes all the necessary WordPress stuff – is this possible?

Thanks for your help!