Answer
Mertens won the Johan Cruyff Shield with PSV in 2012. The Johan Cruyff Shield is an annual Dutch football match contested between the winner of the Eredivisie and the winner of the KNVB Cup. PSV won the Eredivisie title in the 2011-12 season, while Mertens was a key player for the team, scoring 14 goals in 33 league appearances.