In November 1998, Vlascenko won his first Grand Prix medal, bronze at the Sparkassen Cup on Ice. After placing 6th at the 1998 Trophée Lalique and 4th at the 1998 NHK Trophy, he qualified for the Grand Prix Final and went on to win his fourth German national title. In January 1999, he placed fourth (second in his qualifying group, sixth in the short, and fourth in the free) at the European Championships in Prague, Czech Republic. In March, he placed sixth at the Grand Prix Final in Saint Petersburg, Russia, and then 9th at the 1999 World Championships in Helsinki, Finland.