The 29-year-old defender joined the Red Devils back in September on an emergency deal.
Sadler has made seven appearances in all competitions for John Gregory's side during his time at Broadfield Stadium.
Crawley continue their League One campaign on Saturday when they make the trip to Notts County.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 14 | 10 | 2 | 2 | 32 | 16 | 16 | 32 |
| 2 | Birmingham CityBirmingham | 13 | 9 | 3 | 1 | 24 | 12 | 12 | 30 |
| 3 | Wrexham | 14 | 8 | 4 | 2 | 22 | 10 | 12 | 28 |
| 4 | Barnsley | 14 | 7 | 4 | 3 | 23 | 18 | 5 | 25 |
| 5 | Lincoln CityLincoln | 14 | 7 | 4 | 3 | 21 | 17 | 4 | 25 |
| 6 | Stockport CountyStockport | 15 | 6 | 6 | 3 | 25 | 17 | 8 | 24 |
| 7 | Mansfield TownMansfield | 13 | 7 | 3 | 3 | 20 | 15 | 5 | 24 |
| 8 | Huddersfield TownHuddersfield | 14 | 7 | 2 | 5 | 21 | 14 | 7 | 23 |
| 9 | Reading | 14 | 7 | 2 | 5 | 22 | 21 | 1 | 23 |
| 10 | Bolton WanderersBolton | 14 | 7 | 2 | 5 | 22 | 24 | -2 | 23 |
| 11 | Exeter CityExeter | 13 | 7 | 1 | 5 | 14 | 10 | 4 | 22 |
| 12 | Peterborough UnitedPeterborough | 15 | 6 | 3 | 6 | 31 | 27 | 4 | 21 |
| 13 | Charlton AthleticCharlton | 14 | 5 | 4 | 5 | 15 | 15 | 0 | 19 |
| 14 | Stevenage | 15 | 5 | 3 | 7 | 11 | 16 | -5 | 18 |
| 15 | Rotherham UnitedRotherham | 15 | 4 | 5 | 6 | 14 | 18 | -4 | 17 |
| 16 | Bristol Rovers | 14 | 5 | 2 | 7 | 16 | 21 | -5 | 17 |
| 17 | Northampton TownNorthampton | 14 | 4 | 4 | 6 | 18 | 21 | -3 | 16 |
| 18 | Blackpool | 14 | 4 | 4 | 6 | 21 | 28 | -7 | 16 |
| 19 | Wigan AthleticWigan | 14 | 3 | 5 | 6 | 12 | 12 | 0 | 14 |
| 20 | Leyton Orient | 14 | 4 | 2 | 8 | 14 | 18 | -4 | 14 |
| 21 | Crawley TownCrawley | 15 | 3 | 3 | 9 | 14 | 27 | -13 | 12 |
| 22 | Cambridge UnitedCambridge | 13 | 3 | 1 | 9 | 12 | 23 | -11 | 10 |
| 23 | Burton Albion | 14 | 1 | 5 | 8 | 15 | 25 | -10 | 8 |
| 24 | Shrewsbury TownShrewsbury | 15 | 2 | 2 | 11 | 13 | 27 | -14 | 8 |
| > League One Full Table | |||||||||
