In the first half of their debut season in Liga I, Concordia failed to impress, and never left the relegation places. In the mid-season, Laurenţiu Reghecampf was brought as manager, and he changed almost the entire squad, bringing 17 new players. Little by little, the team started to win, among its victims being bigger names like Oţelul Galaţi, Rapid and the future champions CFR Cluj. As a result, the club climbed outside the relegation zone and finished the season in the first half of the table (ninth place). Because of this impressive results, after the season, Reghecampf was named manager at Steaua Bucureşti. His place at Concordia was taken by Ilie Stan. Under his spell, Concordia maintained its place in the upper half of the standings for the first half of the 2012-13 season. But in the second half the team failed to find the same rhythm and after six consecutive losses, Concordia entered the battle to avoid relegation. With a total of 16 games in a row without a win, Concordia finished the season on the 15th spot, similar with a relegation to Liga II after two years in the first division. At the end of the season, Ilie Stan resigned, alongside his entire technical team.Ionuț Chirilă replaced Stan as manager of the theam. Concordia Chiajna successfully remained in the first division, playing a relegation play-off with Rapid. The play-off was played on 13 July 2013 and won by Rapid, with 2-1, after extra-time. The FRF decision was contested by Concordia at the Court of Arbitration for Sport. On 2 August, CAS decided that Concordia Chiajna should play in Liga I and Rapid is relegated to second division. The results of the matches played by Rapid with Viitorul and Vaslui were canceled.