The Belgian, on loan from Manchester United, picked up the injury during the Black Cats' 3-2 defeat against Crystal Palace on Saturday.
A scan on Tuesday confirmed that the 21-year-old has suffered ankle ligament damage and is expected to be out until November at the earliest.
Januzaj has scored once for the Premier League's bottom side in seven appearances.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Liverpool | 6 | 5 | 0 | 1 | 12 | 2 | 10 | 15 |
| 2 | Manchester CityMan City | 6 | 4 | 2 | 0 | 14 | 6 | 8 | 14 |
| 3 | Arsenal | 6 | 4 | 2 | 0 | 12 | 5 | 7 | 14 |
| 4 | Chelsea | 6 | 4 | 1 | 1 | 15 | 7 | 8 | 13 |
| 5 | Aston Villa | 6 | 4 | 1 | 1 | 12 | 9 | 3 | 13 |
| 6 | Fulham | 6 | 3 | 2 | 1 | 8 | 5 | 3 | 11 |
| 7 | Newcastle UnitedNewcastle | 6 | 3 | 2 | 1 | 8 | 7 | 1 | 11 |
| 8 | Tottenham HotspurSpurs | 6 | 3 | 1 | 2 | 12 | 5 | 7 | 10 |
| 9 | Brighton & Hove AlbionBrighton | 6 | 2 | 3 | 1 | 10 | 8 | 2 | 9 |
| 10 | Nottingham ForestNott'm Forest | 6 | 2 | 3 | 1 | 6 | 5 | 1 | 9 |
| 11 | Brentford | 6 | 2 | 1 | 3 | 8 | 10 | -2 | 7 |
| 12 | Manchester UnitedMan Utd | 6 | 2 | 1 | 3 | 5 | 8 | -3 | 7 |
| 13 | Bournemouth | 5 | 1 | 2 | 2 | 5 | 8 | -3 | 5 |
| 14 | West Ham UnitedWest Ham | 6 | 1 | 2 | 3 | 6 | 10 | -4 | 5 |
| 15 | Ipswich TownIpswich | 6 | 0 | 4 | 2 | 5 | 10 | -5 | 4 |
| 16 | Everton | 6 | 1 | 1 | 4 | 7 | 15 | -8 | 4 |
| 17 | Leicester CityLeicester | 6 | 0 | 3 | 3 | 8 | 12 | -4 | 3 |
| 18 | Crystal Palace | 6 | 0 | 3 | 3 | 5 | 9 | -4 | 3 |
| 19 | Southampton | 5 | 0 | 1 | 4 | 2 | 9 | -7 | 1 |
| 20 | Wolverhampton WanderersWolves | 6 | 0 | 1 | 5 | 6 | 16 | -10 | 1 |
| > Premier League Full Table | |||||||||
