Greenwood started Getafe's La Liga clash with Osasuna on the bench but was introduced with 15 minutes of normal time remaining as a substitute for forward Juanmi Latasa.
The 21-year-old was targeted by Osasuna fans after he took to the pitch at the Coliseum Alfonso Perez. Supporters were heard chanting "Greenwood, die," as reported by The Athletic's Guillermo Rai.
Greenwood's appearance was his first competitive outing since January 2022, when he last featured for Manchester United.
The forward was suspended by the club after being arrested on suspicion of attempted rape, assault and coercive control, but saw all charges against him dropped in February. He moved to Getafe on deadline-day on a season-long loan after the Red Devils announced he would be leaving the club following the conclusion of an internal investigation.
Greenwood's first appearance for Getafe ended in a 3-2 win for the hosts. The game was level at 2-2 when the United loanee took to the pitch, but the hosts won it late on through Nemanja Maksimovic's 86th-minute goal.
The win is just Getafe's second of the season so far in the 2023-24 La Liga campaign. Jose Bordalas's side are back in action in a week's time when they head to Anoeta to face Real Sociedad.
