James Kielt hit 1-9 as Derry earned a 1-18 to 2-10 win over Louth in the All-Ireland SFC qualifiers first round.
Louth, playing six days after losing to Meath in Leinster, led by 1-5 to 0-7 at half-time at Owenbeg thanks to Jim McEneaney's 15th-minute penalty.
Derry hit seven points in a row in the second half but Declan Byrne's penalty helped cut the margin to only one.
However, Kielt's superb penalty sealed Derry's win as Byrne received a straight red card in injury time.
Injuries to Thomas Mallon and Callum Mullan-Young, meant 38-year-old goalkeeping coach Michael Conlan started between the posts for the Oak Leafers, five years after his last inter-county game.
Louth midfielder James Califf hit three frees in the first half while Christopher Bradley (0-2) and Kielt provided the bulk of Derry's scores.
The two-man full-forward line of Mark Lynch and Emmet McGuckin was potent for Derry but the Oak Leafers missed a lot of chances, forcing Louth goalkeeper Craig Lynch to make three saves.
Referee Marty Duffy awarded Louth a penalty when McEneaney was pushed after trying to connect with Conor Grimes' pass across the square.
He stepped up and drilled the ball low past Conlan.
Louth wilted badly in the second half as Derry hit seven unanswered points.
Kielt punished every Louth foul inside the 50 metre mark and they led 1-15 to 1-7 after 59 minutes.
However, Declan Byrne jinked inside and buried the ball high into the net for Louth's second goal to help bring his team to within a point of Damian Barton's side.
However Kielt settled it with a free and an expertly-taken penalty in the 66th minute, after Danny Heavron was hauled down in the square and the Oak Leafers could afford the luxury of a late penalty miss by the man of the match.
All-Ireland SFC Qualifiers
Laois 1-10 0-10 Armagh
Derry 1-18 2-10 Louth
Carlow 1-17 1-12 Wicklow
Connacht SFC semi-final
Mayo 0-12 1-12 Galway
All-Ireland SFC qualifiers
Leitrim v Waterford (Carrick-on-Shannon, 14:00)
Ulster SFC semi-final
Tyrone v Cavan (Clones, 14:00)
Ulster SHC semi-finals
Derry v Antrim (Athletic Grounds, 17:00)
Down v Armagh (Athletic Grounds, 19:00)
Munster SHC semi-final
Tipperary v Limerick (Thurles, 15:30)
Leinster SHC semi-final
Galway v Offaly (Portlaoise, 15:30)