Merk was referee in the 1992 Olympics (two call-ups), fourth official in the 1993 World Cup qualifier between the Netherlands and England (During this match Merk repeatedly restrained the furious England manager Graham Taylor, when a penalty and red card decision had gone against England. Taylor felt Ronald Koeman should have been sent off and England have a penalty for a professional foul on David Platt. Neither happened and Koeman went on to score against England. Taylor was furious at the referee, though years later, in an interview with the Observer, he expressed gratitude to Merk for not sending him to the stands when he could have), the UEFA Euro 2000 (3), the 2002 FIFA World Cup (2) and the UEFA Euro 2004 (3). In that tournament, he also whistled the final, becoming the first German referee since Rudi Glöckner of East Germany in 1970, to helm a World Cup or European Championship Finals. His assistants were Jan-Hendrik Salver and Christian Schräer. Merk also refereed the 1997 UEFA Cup Winners' Cup Final, and the 2003 UEFA Champions League Final. He was the referee in the semi final of the 2003 FIFA Confederations Cup between Cameroon and Colombia, a game remembered for the death of Marc-Vivien Foé.