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 | Wrexham | 7 | 5 | 1 | 1 | 14 | 6 | 8 | 16 |
| 2 | Birmingham CityBirmingham | 6 | 5 | 1 | 0 | 13 | 6 | 7 | 16 |
| 3 | Barnsley | 7 | 4 | 1 | 2 | 12 | 10 | 2 | 13 |
| 4 | Charlton AthleticCharlton | 7 | 4 | 1 | 2 | 7 | 5 | 2 | 13 |
| 5 | Huddersfield TownHuddersfield | 6 | 4 | 0 | 2 | 11 | 6 | 5 | 12 |
| 6 | Stockport CountyStockport | 6 | 3 | 2 | 1 | 10 | 6 | 4 | 11 |
| 7 | Lincoln CityLincoln | 6 | 3 | 2 | 1 | 10 | 6 | 4 | 11 |
| 8 | Mansfield TownMansfield | 6 | 3 | 2 | 1 | 11 | 11 | 0 | 11 |
| 9 | Wycombe WanderersWycombe | 6 | 3 | 1 | 2 | 12 | 10 | 2 | 10 |
| 10 | Peterborough UnitedPeterborough | 6 | 3 | 1 | 2 | 10 | 9 | 1 | 10 |
| 11 | Exeter CityExeter | 6 | 3 | 0 | 3 | 8 | 6 | 2 | 9 |
| 12 | Northampton TownNorthampton | 6 | 2 | 2 | 2 | 8 | 7 | 1 | 8 |
| 13 | Blackpool | 6 | 2 | 2 | 2 | 11 | 13 | -2 | 8 |
| 14 | Wigan AthleticWigan | 6 | 2 | 1 | 3 | 6 | 5 | 1 | 7 |
| 15 | Stevenage | 6 | 2 | 1 | 3 | 5 | 5 | 0 | 7 |
| 16 | Reading | 6 | 2 | 1 | 3 | 7 | 10 | -3 | 7 |
| 17 | Crawley TownCrawley | 6 | 2 | 1 | 3 | 5 | 8 | -3 | 7 |
| 18 | Bolton WanderersBolton | 6 | 2 | 1 | 3 | 7 | 11 | -4 | 7 |
| 19 | Bristol Rovers | 7 | 2 | 1 | 4 | 6 | 11 | -5 | 7 |
| 20 | Leyton Orient | 6 | 2 | 0 | 4 | 7 | 9 | -2 | 6 |
| 21 | Rotherham UnitedRotherham | 7 | 1 | 3 | 3 | 5 | 9 | -4 | 6 |
| 22 | Burton Albion | 6 | 0 | 4 | 2 | 8 | 10 | -2 | 4 |
| 23 | Shrewsbury TownShrewsbury | 7 | 1 | 0 | 6 | 5 | 12 | -7 | 3 |
| 24 | Cambridge UnitedCambridge | 6 | 0 | 1 | 5 | 6 | 13 | -7 | 1 |
| > League One Full Table | |||||||||
