A daunting task awaits John Mousinho and his Pompey side as Premier League leaders Arsenal make the trip to Fratton Park.
The Gunners, who are the highest seed in the competition, visit PO4 for the first time in six years to face the Blues who are in the midst of an injury crisis.
Mousinho’s side, meanwhile, welcome Mikel Arteta’s side off the back of a 5-0 defeat to Bristol City on New Year’s Day after their game against Ipswich Town last week was postponed.
We’ve taken a look at the early team and injury news from both camps ahead of Sunday’s third-round tie.
Your next Pompey read: Conor Chaplin's Portsmouth stay thrown into doubt by Ipswich boss Kieran McKenna
5. Mark Kosznovszky - Out
Kosznovszky’s maiden campaign at Fratton Park is over after tearing his ACL and MCL late in the triumph over Charlton. The Hungarian is now set for 9-12 months on the sidelines. | Graham Hunt/ProSportsImages
6. Max Dowman - Out
Dowman has been sidelined since December after picking up an ankle injury in a behind-closed-doors friendly against Manchester United. The 16-year-old is expected to return in February. | AFP via Getty Images
7. Josh Murphy - Out
Murphy has been a significant absentee for the Blues over the past two weeks after suffering a hamstring problem against Derby County before Christmas. The winger is still at least three weeks away from a potential return to the side. | Graham Hunt/ProSportsImages
8. Marlon Pack - Doubt
Pack is one of two members from Mousinho’s squad who could return from the sidelines to face Arsenal. The head coach is hopeful the skipper will be fit after missing Bristol City due to a slight hamstring issue. | Graham Hunt