Tareiq Holmes-Dennis has suffered a long-term injury while on loan at Portsmouth.
The Huddersfield Town left-back joined Pompey over the summer in a bid for first-team football, but lasted just 39 minutes before leaving the field in Portsmouth's first match.
During Pompey's League One opener against Rochdale, the 21-year-old suffered a knee injury which will keep him sidelined for around four months.
The 2017/18 Premier League season
The south coast club's manager Kenny Jackett told BBC Radio Solebt on Tuesday: "It's not good news, it looks longer-term rather than short-term, which is a blow as he had a bright pre-season for us."
Holmes-Dennis will return Town for his rehabilitation.
The defender made 15 appearances for Town last season from the bench and starting, keeping seven clean sheets in the process.