Bristol City defender Christian Ribeiro has suffered anterior cruciate ligament damage and is facing 12 months on the sidelines.
The 18-year-old was making his first-team debut against Peterborough in the Carling Cup first round on Tuesday evening when he sustained the injury.
Ribeiro will now undergo surgery before the weekend ahead of a lengthy spell out of action.
City manager Gary Johnson told the club's official website: "Everyone is gutted for Christian.
"It is hard luck on the lad, 20 minutes into his debut. But as I said on the night, he will come back from this.
"He is young, fit and strong. He is only 18 and he has time on his side.
"It will seem a long way back at the moment but we will give him all our time and attention."

League One Round Up - 21st November
Tottenham v Wigan - 2nd Half
Championship Round Up - 21st November
League Two Round Up - 21st November
Tottenham v Wigan - 1st Half
Stoke 1-0 Portsmouth - Fuller and Sorensen
Tottenham 9-1 Wigan - Defoe
Stoke 1-0 Portsmouth - Pulis
| Time | Fixture |
|---|---|
| Wednesday 25th November | |
| Barclays Premier League | |
| 19:45 | Hull vs Everton |
| 20:00 | Fulham vs Blackburn |
| Saturday 28th November | |
| Barclays Premier League | |
| 15:00 | Blackburn vs Stoke |
| 15:00 | Fulham vs Bolton |
| 15:00 | Man City vs Hull |
| 15:00 | Portsmouth vs Man Utd |
| 15:00 | West Ham vs Burnley |
| 15:00 | Wigan vs Sunderland |
| 17:30 | Aston Villa vs Tottenham |
| Sunday 29th November | |
| Barclays Premier League | |
| 12:00 | Wolverhampton vs Birmingham |
| 13:30 | Everton vs Liverpool |
| 16:00 | Arsenal vs Chelsea |
| Saturday 5th December | |
| Barclays Premier League | |
| 12:45 | Portsmouth vs Burnley |
| 15:00 | Arsenal vs Stoke |
| 15:00 | Aston Villa vs Hull |
| 15:00 | Blackburn vs Liverpool |
| 15:00 | West Ham vs Man Utd |
| 15:00 | Wigan vs Birmingham |
| 15:00 | Wolverhampton vs Bolton |
| 17:30 | Man City vs Chelsea |
| Time | Result |
|---|---|
| Sunday 22nd November | |
| Barclays Premier League | |
| Bolton 0 - 2 Blackburn | |
| Tottenham 9 - 1 Wigan | |
| Stoke 1 - 0 Portsmouth | |
| Saturday 21st November | |
| Barclays Premier League | |
| Liverpool 2 - 2 Man City | |
| Hull 3 - 3 West Ham | |
| Sunderland 1 - 0 Arsenal | |
| Chelsea 4 - 0 Wolverhampton | |
| Man Utd 3 - 0 Everton | |
| Birmingham 1 - 0 Fulham | |
| Burnley 1 - 1 Aston Villa | |
| Monday 9th November | |
| Barclays Premier League | |
| Liverpool 2 - 2 Birmingham | |
| Sunday 8th November | |
| Barclays Premier League | |
| Hull 2 - 1 Stoke | |
| Wigan 1 - 1 Fulham | |
| Chelsea 1 - 0 Man Utd | |
| West Ham 1 - 2 Everton | |
| Saturday 7th November | |
| Barclays Premier League | |
| Aston Villa 5 - 1 Bolton | |
| Blackburn 3 - 1 Portsmouth | |
| Tottenham 2 - 0 Sunderland | |
| Wolverhampton 1 - 4 Arsenal | |
| Man City 3 - 3 Burnley | |
Get involved in the Sky Sports debate following the latest round of Premier League games.
Skysports.com looks at the best and worst moments from the latest round of top-flight fixtures.
Pictures from Saturday's action where Liverpool draw with Man City and Arsenal lose away.
Jermain Defoe helped himself to five goals as Tottenham demolished Wigan 9-1 at White Hart Lane to move into fourth spot in the table.
Follow all the action from Sunday's packed programme with the skysports.com Score Centre.
Bolton squandered the chance to climb out of the bottom three as they were beaten 2-0 at home by Blackburn.
Paul Hart played down the injury to David James prior to Portsmouth's 1-0 defeat to Stoke on Sunday.
Stoke collected all three points against Portsmouth thanks to a late strike from Ricardo Fuller.