Pompey have been drawn away to Championship side Millwall in the first round of the Carabao Cup.
The tie is scheduled to take place at The Den in the week commencing August 9, although sides can mutually agree to an earlier date.
It will be the first meeting between the sides since both were in the Championship during the 2011/12 campaign.
The clubs – neither of whom have progressed further than the quarter-finals – have never previously clashed in the League Cup.
Pompey won on penalties at Stevenage at this stage of last season's competition before exiting at the hands of top-flight Brighton.
Milwall also fell to Premier League opposition, losing to Burnley in the third round after beating Crawley and Cheltenham.
Gary Rowett's side – who have former Fratton favourites Ben Thompson and Jed Wallace in their ranks – finished the 2020/21 Championship campaign in 11th position.
|Carabao Cup Round One – South|
|Cambridge United v Swindon Town|
|Exeter City v Wycombe Wanderers|
|Crawley Town v Gillingham|
|Burton Albion v Oxford United|
|Coventry City v Northampton Town|
|Ipswich Town v Newport County|
|Forest Green Rovers v Bristol City|
|Reading v Swansea City|
|Cardiff City v Sutton United|
|AFC Bournemouth v Milton Keynes Dons|
|Bristol Rovers v Cheltenham Town|
|Peterborough United v Plymouth Argyle|
|Leyton Orient v Queens Park Rangers|
|Stevenage v Luton Town|
|Millwall v POMPEY|
|Birmingham City v Colchester United|
|Charlton Athletic v AFC Wimbledon|
|Carabao Cup Round One – North|
|Sheffield Wednesday v Huddersfield Town|
|Derby County v Salford City|
|Hartlepool United v Crewe Alexandra|
|Shrewsbury Town v Lincoln City|
|Mansfield Town v Preston North End|
|Port Vale v Sunderland|
|Sheffield United v Carlisle United|
|Blackpool v Middlesbrough|
|Harrogate Town v Rochdale|
|Stoke City v Fleetwood Town|
|Walsall v Doncaster Rovers|
|Oldham Athletic v Tranmere Rovers|
|Rotherham United v Accrington Stanley|
|Barrow v Scunthorpe United|
|Hull City v Wigan Athletic|
|Bolton Wanderers v Barnsley|
|Nottingham Forest v Bradford City|
|Blackburn Rovers v Morecambe|