Going into the 1987 outdoor season, Sedláková won her first outdoor title at the Czechoslovak Athletics Championships. Her winning time of 2:00.42 minutes was another new best and the third-fastest ever winning time at the competition (only Jozefína Čerchlanová and Jarmila Kratochvílová had run faster). One week before the 1987 World Championships in Athletics she raised herself as a possible contender with another best at the Internationales Stadionfest meet in West Berlin, running 1:58.37 minutes. This proved to be her lifetime best and ultimately ranked her 15th globally on time that year. At the championships in Rome she narrowly missed the final, coming fourth in her semi-final.