| U20 World Cup 1999 Nigeria - Appearances as Referee |  |
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| 05/04/1999 | Cameroon | - | Japan | 2:1 | 2 | - | - |
| 08/04/1999 | Cameroon | - | England | 1:0 | 5 | - | - |
| 18/04/1999 | Spain | - | Ghana | 8:7 pso | 11 | - | 1 |
| U20 World Cup 1999 Nigeria - Appearances as Referee | |
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| 05/04/1999 | Cameroon | - | Japan | 2:1 | 2 | - | - |
| 08/04/1999 | Cameroon | - | England | 1:0 | 5 | - | - |
| 18/04/1999 | Spain | - | Ghana | 8:7 pso | 11 | - | 1 |
| Complete name: | William Mattus Vega |
| Born: | 17/04/1964 |
| Place of birth: |
Costa Rica |
| Nationality: |
Costa Rica |
| Height: | 169 cm |
| Weight: | 75 kg |