The first football semi-final in the national stadium since it was closed for its Commonwealth Games transformation is certain to be over half-full.
United are approaching 8,000 tickets sold, while Aberdeen have broken 19,000.
Tickets are now on general sale and Dons supporters can buy tickets by phone or online - click here to find out full details.
Meanwhile, the rules for supporters' flag displays have been announced.
Flags on poles not exceeding 1m in length will be allowed in all parts of the ground.
Surfing flags are not allowed in the ground, and no flags can be displayed over the advertising boards or obstructing passageways.
Flares are also not allowed, so most Dundee Utd supporters are likely to be forced to change their trousers. No pyro no party, but as long as Adam Rooney's having a party we'll be happy.