The 22-year-old Spaniard was part of the Bilbao side that dumped United out of the Europa League last month.
Reds boss Sir Alex Ferguson is thought to have had the player scouted twice in recent weeks, according to The Mirror.
However, the Premier League champions may be reluctant to pay the £26m release clause in De Marcos's contract.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Arsenal | 33 | 23 | 5 | 5 | 77 | 26 | 51 | 74 |
| 2 | Liverpool | 33 | 22 | 8 | 3 | 75 | 32 | 43 | 74 |
| 3 | Manchester CityMan City | 32 | 22 | 7 | 3 | 76 | 32 | 44 | 73 |
| 4 | Aston Villa | 34 | 20 | 6 | 8 | 71 | 50 | 21 | 66 |
| 5 | Tottenham HotspurSpurs | 32 | 18 | 6 | 8 | 65 | 49 | 16 | 60 |
| 6 | Newcastle UnitedNewcastle | 32 | 15 | 5 | 12 | 69 | 52 | 17 | 50 |
| 7 | Manchester UnitedMan Utd | 32 | 15 | 5 | 12 | 47 | 48 | -1 | 50 |
| 8 | West Ham UnitedWest Ham | 34 | 13 | 9 | 12 | 54 | 63 | -9 | 48 |
| 9 | Chelsea | 31 | 13 | 8 | 10 | 61 | 52 | 9 | 47 |
| 10 | Brighton & Hove AlbionBrighton | 32 | 11 | 11 | 10 | 52 | 50 | 2 | 44 |
| 11 | Wolverhampton WanderersWolves | 33 | 12 | 7 | 14 | 46 | 53 | -7 | 43 |
| 12 | Fulham | 34 | 12 | 6 | 16 | 50 | 54 | -4 | 42 |
| 13 | Bournemouth | 33 | 11 | 9 | 13 | 48 | 60 | -12 | 42 |
| 14 | Crystal Palace | 33 | 9 | 9 | 15 | 42 | 56 | -14 | 36 |
| 15 | Brentford | 34 | 9 | 8 | 17 | 52 | 59 | -7 | 35 |
| 16 | Everton | 33 | 10 | 8 | 15 | 34 | 48 | -14 | 30 |
| 17 | Nottingham ForestNott'm Forest | 34 | 7 | 9 | 18 | 42 | 60 | -18 | 26 |
| 18 | Luton TownLuton | 34 | 6 | 7 | 21 | 47 | 75 | -28 | 25 |
| 19 | Burnley | 34 | 5 | 8 | 21 | 37 | 69 | -32 | 23 |
| 20 | Sheffield UnitedSheff Utd | 33 | 3 | 7 | 23 | 31 | 88 | -57 | 16 |
| > Premier League Full Table | |||||||||
