His first goal for East Germany was at their fifth qualifying match of the UEFA Euro 1984, against Switzerland at the Berlin Jahn-Sportpark. In the 73rd minute Ersnt received a pass from Joachim Streich and elegantly lobbed Swiss Goalkeeper Roger Berbig from 22 meters. Joachim Streich added another goal at 94 minutes to make the game 3–0, their first win in five qualifying matches. Ernst played as number 10 for their sixth qualifying match of the 1986 FIFA World Cup against France in a fully-filled Zentralstadion on 11 September 1985. He converted Andreas Thom's cross with a header at 53 minutes into the match, which brought the team a 1–0 lead. And he overtook four French players with his 40-meter-solo dribbling, whistles (at BFC Dynamo players) fell silent and he gained the whole stadium's sympathy. The match resulted 2–0 victory over the European champions.