Millwall finished third in the Championship but lost to Hull City in the play-off semi-finals, ending their season. Hull City won 2-0 on aggregate, advancing to the final at Wembley.
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Millwall finished third in the Championship before losing to Hull City in the play-off semi-finals [Shutterstock]
As the referee blew the final whistle at The Den on Monday, he brought an end to Millwall's season with it.
Second-half goals from Mo Belloumi and Joe Gelhardt secured a 2-0 aggregate victory for Hull City that sent the Tigers into the Championship play-off final at Wembley and ensured the Lions will remain in the second tier for at least one more season.
This campaign has been full of moments when manager Alex Neil's substitutions have helped turn defeats into draws and draws into wins.
But in a match in which two Hull players scored after being brought off the bench, nothing went right for Millwall as they looked to win promotion to the Premier League for the first time in its modern form.
Within a minute of being introduced in the second half, Alfie Doughty failed to get tight to Belloumi wide on Millwall's left, with the Algerian able to cut in and score a sumptuous and critical opening goal.
Millwall were suddenly 1-0 down in the tie after 64 minutes of the second leg, having already turned to their bench three times, with Barry Bannan coming on alongside Doughty and Mihailo Ivanovic introduced to partner Josh Coburn up front six minutes earlier.
Neil told BBC Radio London after the game: "It's been a great season but at the moment all you feel is disappointment and frustration.
Millwall finished third in the Championship.
Millwall lost to Hull City in the play-off semi-finals.
The aggregate score was 2-0 in favor of Hull City.
Manager Alex Neil's substitutions often turned defeats into draws and draws into wins throughout the season.

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"You feel as if naturally you've let people down; the supporters, the hierarchy, things like that. That's part and parcel of being a manager."
It might have ended in disappointment, but it has unquestionably been a fantastic season for Millwall.
Finishing third in the table, their total of 83 points is higher than the 82 that the Second Division title-winners of 1987-88 accrued, albeit in a 44-game season.
No team this season equalled their tally of 18 Championship clean sheets - 19, if you include the goalless semi-final first leg on Friday.
And they were still very much in the automatic promotion race right up to kick-off on the final day. Had Ipswich Town slipped up against Queens Park Rangers, they would have been promoted with Coventry City.
There will undoubtedly be "what if?" moments that fans will look back on.
Ryan Leonard's disallowed goal at MKM Stadium comes to mind, or the draw at already-relegated Leicester City in the penultimate game of the season, which would have put them in the driving seat going into their last game against Oxford United.
Then there was the red card shown to Zak Sturge when the Lions were 1-0 up against Blackburn in March before eventually losing 2-1 - a decision that was swiftly overturned retrospectively as the referee had deemed him to be the last man but with Jake Cooper covering.
However, Neil chose not to focus on those moments and instead reflect more positively on the season.
Tristan Crama made 50 appearances for Millwall this season, scoring three goals [Getty Images]
The Scot said: "Did I roll the dice too early? Did I go for it?
"There are loads of bits running through your mind and then even when I'm speaking to Sky they're saying 'do you think three weeks ago if you won that game...' and I'm thinking 'come on, how far do you want to go back?'
"Do you want to go back to the start of the season? Every team can do that across the season.
"It's been one of my favourite seasons as a coach because the group have given me so much, the fans have got right behind the team, the owners of the club have given me nothing but complete support, so from that perspective I can only be thankful for that.
"I'm just sorry that we didn't do enough."
While Hull can turn their attention to the final against either Middlesbrough or Southampton at Wembley on Saturday, 23 May, Millwall's focus will turn to preparing the squad to go again next season and try to go one better - be that through automatic promotion or a successful play-off campaign.
"Every year, it's been year-on-year progression," former Millwall striker Steve Morison said.
"The teams coming down are going to be huge in the Championship so they need to savour this moment.
"I think they've shown they've consistently improved. What that looks like, I don't know, but they need to improve against teams that don't have the ball.
"From a Millwall point of view, you'd be gutted but proud of the football club."