James McClean was on target for Albion who gained a valuable pre-season workout in a 2-1 defeat to Slavia Prague in Kumberg on Wednesday.
The game brought an end to the Baggies' gruelling eight-day training camp in Austria, with Jonny Evans pulling on the captain's armband for the friendly against the Czech champions.
McClean opened the scoring for the Baggies in the 26th minute after rounding Prague 'keeper Jan Lastuvka and slotting into an empty net.
The Irish international was sent clean through after an incisive through-ball from Matt Phillips and made no mistake from five yards.
Tony Pulis made a host of changes at half-time, with a young Albion XI starting the second period - including trialist Jason Lowe.
But Prague got their equaliser just five minutes after the restart, with Simon Deli turning past Boaz Myhill from a corner.
Dara O'Shea hit the bar from a Callum McManaman corner midway through the second half but Michal Frydrych slotted home the winner for Prague in the 77th minute.