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
9. Riccardo Calafiori - Out
The Italy international has missed the Gunners’ previous three matches due to an awkward muscle injury and is continuing his rehab. | AFP via Getty Images
10. Hayden Matthews - Out
The centre-back sustained an ankle injury against Bristol City, which forced him off late in the contest. Matthews will now miss up to 8-10 weeks of action - but won’t require surgery. | Graham Hunt/ProSportsImages
11. Thomas Waddingham - Out
Waddingham is another of the Blues’ long-term absentees and has been pencilled in to complete his comeback from a quad injury next month. | Manjit Narotra/ProSportsImages
12. Kai Havertz - Doubt
The German sustained a knee injury at the beginning of the season and returned to the squad for the first time against Aston Villa at the end of December. Arteta has revealed the forward still needs to build up match fitness. | Getty Images