Tickets for Albion's trip to Reading on Wednesday will be available to purchase on the day of the game (ko 8pm).
The Baggies have sold out their initial 1,500-seat allocation, but the hosts have now made extra tickets available for sale at the Madejski Stadium on matchday.
Supporters looking to back Slaven's side can call Reading's ticket office on 0118 968 1313, selecting option 1, from 9am on Wednesday.
Alternatively, fans can purchase tickets in-person from Reading's South Stand Ticket Office, which will be open from 6.30pm on matchday.
Please note, tickets for this fixture are no longer available to purchase from The Hawthorns Ticket Office.