After years as a II division or lower-table I division side in East Germany, Energie emerged as one of the few former DDR sides to enjoy relative prosperity in a united Germany. After six seasons playing tier III football, the club earned promotion to the 2. Bundesliga in 1997 (the same year they became the first former East German club to play the DFB Cup Final), winning the Regionalliga Nordost, and then played its way into the Bundesliga in 2000, where it managed a three-year stay. A key player in the Bundesliga run was Vasile Miriuță, an imaginative midfield player who played a large part in the team's promotion. After being relegated, Energie narrowly missed a prompt return to the top tier, losing out to Mainz 05 on goal differential. In 2004–05, Energie struggled into both financial (reported debts of €4.5 million) and sports problems: the season goal of promotion was missed by far – the club escaped the relegation to third tier Regionalliga by scoring one more goal (season overall) than Eintracht Trier while having the same number of points and amount of goal differential. During season the manager and the chairman were replaced. Next season (2005–06) was a much more successful one – the club returned to play in the First Division Bundesliga after winning promotion.