The Norwegian, who was sacked by Rovers last year after just 57 days at the helm, will take charge of his new team on January 1.
Legia Warsaw will be Berg's fourth management job, following stints with Norwegian sides Lyn and Lillestrom, as well as Blackburn.
Legia Warsaw are currently top of the Polish top flight with 43 points from 21 matches played.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Slask Wroclaw | 33 | 17 | 9 | 7 | 48 | 30 | 18 | 60 |
| 2 | Jagiellonia BialystokJagiellonia | 32 | 17 | 8 | 7 | 73 | 44 | 29 | 59 |
| 3 | Legia WarsawLegia | 32 | 14 | 11 | 7 | 48 | 38 | 10 | 53 |
| 4 | Gornik ZabrzeGornik | 33 | 15 | 8 | 10 | 45 | 40 | 5 | 53 |
| 5 | Pogon SzczecinSzczecin | 33 | 15 | 7 | 11 | 58 | 38 | 20 | 52 |
| 6 | Rakow CzestochowaRakow | 32 | 14 | 10 | 8 | 53 | 35 | 18 | 52 |
| 7 | Lech Poznan | 32 | 14 | 10 | 8 | 45 | 38 | 7 | 52 |
| 8 | Zaglebie Lubin | 32 | 12 | 8 | 12 | 40 | 47 | -7 | 44 |
| 9 | Stal Mielec | 33 | 11 | 10 | 12 | 40 | 45 | -5 | 43 |
| 10 | Piast GliwicePiast Gliwice | 32 | 9 | 15 | 8 | 37 | 33 | 4 | 42 |
| 11 | Widzew Lodz | 32 | 12 | 6 | 14 | 41 | 44 | -3 | 42 |
| 12 | Radomiak Radom | 33 | 10 | 8 | 15 | 40 | 55 | -15 | 38 |
| 13 | Warta Poznan | 32 | 9 | 10 | 13 | 33 | 39 | -6 | 37 |
| 14 | Puszcza Niepolomice | 33 | 8 | 13 | 12 | 38 | 49 | -11 | 37 |
| 15 | KS CracoviaCracovia | 32 | 7 | 15 | 10 | 43 | 44 | -1 | 36 |
| 16 | Korona Kielce | 33 | 7 | 14 | 12 | 38 | 43 | -5 | 35 |
| 17 | Ruch Chorzow | 33 | 5 | 14 | 14 | 38 | 55 | -17 | 29 |
| 18 | LKS Lodz | 32 | 5 | 6 | 21 | 30 | 71 | -41 | 21 |
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