The striker missed training this morning, leading to speculation regarding his availability.
Manager Sir Alex Ferguson has now confirmed that the 26-year-old is suffering from an illness.
It is not known whether or not Rooney will recover in time for Sunday's Premier League trip to Norwich City.
United head into Thursday's tie with Ajax holding a 2-0 advantage.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Liverpool | 10 | 8 | 1 | 1 | 19 | 6 | 13 | 25 |
| 2 | Manchester CityMan City | 10 | 7 | 2 | 1 | 21 | 11 | 10 | 23 |
| 3 | Nottingham ForestNott'm Forest | 10 | 5 | 4 | 1 | 14 | 7 | 7 | 19 |
| 4 | Chelsea | 10 | 5 | 3 | 2 | 20 | 12 | 8 | 18 |
| 5 | Arsenal | 10 | 5 | 3 | 2 | 17 | 11 | 6 | 18 |
| 6 | Aston Villa | 10 | 5 | 3 | 2 | 17 | 15 | 2 | 18 |
| 7 | Tottenham HotspurSpurs | 10 | 5 | 1 | 4 | 22 | 11 | 11 | 16 |
| 8 | Brighton & Hove AlbionBrighton | 10 | 4 | 4 | 2 | 17 | 14 | 3 | 16 |
| 9 | Fulham | 10 | 4 | 3 | 3 | 14 | 13 | 1 | 15 |
| 10 | Bournemouth | 10 | 4 | 3 | 3 | 13 | 12 | 1 | 15 |
| 11 | Newcastle UnitedNewcastle | 10 | 4 | 3 | 3 | 10 | 10 | 0 | 15 |
| 12 | Brentford | 10 | 4 | 1 | 5 | 19 | 20 | -1 | 13 |
| 13 | Manchester UnitedMan Utd | 10 | 3 | 3 | 4 | 9 | 12 | -3 | 12 |
| 14 | West Ham UnitedWest Ham | 10 | 3 | 2 | 5 | 13 | 19 | -6 | 11 |
| 15 | Leicester CityLeicester | 10 | 2 | 4 | 4 | 14 | 18 | -4 | 10 |
| 16 | Everton | 10 | 2 | 3 | 5 | 10 | 17 | -7 | 9 |
| 17 | Crystal Palace | 10 | 1 | 4 | 5 | 8 | 13 | -5 | 7 |
| 18 | Ipswich TownIpswich | 10 | 0 | 5 | 5 | 10 | 21 | -11 | 5 |
| 19 | Southampton | 10 | 1 | 1 | 8 | 7 | 19 | -12 | 4 |
| 20 | Wolverhampton WanderersWolves | 10 | 0 | 3 | 7 | 14 | 27 | -13 | 3 |
| > Premier League Full Table | |||||||||
