A much-changed Portsmouth side lost their final league match of the season to champions Northampton Town having played most of the second half with ten men.
Paul Cook made his intentions clear as Christian Burgess, Enda Stevens, Danny Hollands and Michael Doyle were all rested ahead of Thursday's far more important match.
Jack Whatmough was one of the players who benefitted from those changes but unfortunately he marked his first start for Pompey this season by diverting Nicky Adams's cross past Brian Murphy and into his own net.
Northampton were the better side in the first half and John Marquis blasted the ball into the Fratton End when he should have scored. Kal Naismith had Pompey's best chance when he was denied as point blank range by Cobblers goalkeeper Adam Smith.
The second half started badly for Pompey as Kieron Freeman, playing in a defensive midfield role, was given a straight red card for a reckless lunge on John-Joe O'Toole. It was a stupid thing to do and he is now ruled out of the play-offs.
That dismissal seemed to energise Pompey, however, and Naismith, who couldn't find the net from one yard, managed to score from over thirty with an absolutely stunning strike that will rival Michael Doyle's at Accrington for the "goal of the season" award.
Pompey began to outplay the champions despite their numerical disadvantage and should have taken the lead when Brandan Haunstrup struck from close range after Adam Smith dropped the ball under pressure from Adam McGurk, but referee Mark Brown harshly penalised McGurk for a foul on the keeper.
Paul Cook's ten men were fairly comfortable despite the manager making changes that saw just one recognised defender in the back four and that was Ben Davies playing at centre back!
The Cobblers took advantage of such a makeshift backline eventually as David Buchanan's cross was turned in by James Collins to confirm Pompey's defeat and, coupled with Plymouth's 5-0 win over Hartlepool, a sixth place finish in League Two.
The result will have no baring on what may happen in the play-offs due to the weakened state of the team. It's unlikely that any of the fringe players who either started or were brought on yesterday will start on Thursday with the exception of Connor Wilkinson.
The Bolton loanee played much like how Michael Smith did before he returned to Swindon. He's a similar build and a willing runner so Cook may be tempted to start him if Marc McNulty and Conor Chaplin are unavailable for Pompey's biggest game for six years.
Whilst the Portsmouth fans could sit back and enjoy the match yesterday, that will simply not be the case on Thursday evening.
Pompey Player Ratings
Brian Murphy: 6 - Couldn't do anything about either goal.
Ben Davies: 6 - Overworked at times but still held his own.
Jack Whatmough: 5 - Own goal wasn't the best way to mark his return but steady otherwise.
Adam Barton: 5 - Probably won't start against Plymouth if Clarke or Webster are fit.
Brandan Haunstrup: 6 - Did a solid job.
Kieron Freeman: 3 - Wasn't particularly great before his daft dismissal. Won't be missed.
Ben Close: 5 - Found it tough at times but hopefully injury isn't too serious.
Gareth Evans: 5 - Not at his best going forward and definitely isn't a right back!
Adam McGurk: 5 - Ineffective.
Kal Naismith: 7 - Superb strike and recent form may see him start on Thursday regardless of Kyle Bennett's availability.
Gary Roberts: 6 - Mixed performance in "false nine" role.
Substitutes
Paul Jones
Enda Stevens
Michael Doyle
Adam May (Close 60): 6 - Didn't look out of place.
Christian Oxlaide-Chamberlain
Ben Tollitt (Haunstrup 77): N/A - Look forward to seeing more of him next season.
Connor Wilkinson (Whatmough 69): N/A - Looks like he could be handy if he is called upon.