Leicester manager Nigel Pearson admitted it was a big wake-up call for his “lacklustre” side after seeing their 21-match unbeaten run in the Sky Bet Championship brought to an emphatic end in a 4-1 home loss to Brighton.
The Foxes may already have sealed promotion to the Barclays Premier League over the weekend but they still have the title to play for and would have been eager to continue their impressive form against Brighton.
However, a second-half brace from Leonardo Ulloa following first-half efforts from Stephen Ward and Jesse Lingard set Brighton on their way to a comprehensive win at the King Power Stadium, with Leicester only able to respond through Gary Taylor-Fletcher's late goal.
Pearson said: "It was really disappointing to put on that sort of performance on what should have been an evening where we were celebrating getting promotion. So that's a big wake up for us.
"We didn't perform like the side we have been this season. I thought we were lacklustre and unfortunately unable to get any sort of momentum.
"We have won promotion and we want to win the title. We have five games left and we can't have performances like that."
Leicester's defeat allowed second-placed Burnley to close the gap between the two to six points with a 1-0 victory at Barnsley, although the Clarets' main aim at present is just to secure promotion.
They could do that this weekend if they beat Middlesbrough at Turf Moor and third-placed Derby lose at home against Huddersfield, and manager Sean Dyche was quick to turn his attention to the visit of Boro following the win at Oakwell.
"The next game for us is a big one," said Dyche. "We've been focusing on it all season and that won't change.
"I've already told the players to enjoy tonight, but we're already prepping, recovering already and getting ready for the weekend."
Burnley's cause was helped by three of the four teams immediately below them losing on Tuesday night.
QPR were beaten 2-0 at Blackburn, allowing Derby to replace them in third spot with a 3-1 win at Blackpool, while the other sides in the play-off spots, FA Cup semi-finalists Wigan and Reading, lost 1-0 at home to Millwall and 3-1 at Bournemouth respectively.
Those results have allowed a number of teams to close the gap on the top six, with Brighton, Ipswich and Bournemouth now just two points behind Reading following wins on Tuesday.
Ipswich are aiming to reach the play-offs for the first time since 2005 but manager Mick McCarthy was keeping it low key following their 2-0 win at Huddersfield.
He said: "It may be two points but we have a worse goal difference so it's really three."
For beaten Huddersfield, the result left them without a win in eight Championship matches and manager Mark Robins was scathing of his team's display, saying: "It was the most abject performance of any team I have managed and it cannot happen again.
"I have never apologised before but I feel I have to because that was horrendous."
Also on Tuesday, Leeds suffered an eighth defeat in nine matches after going down 3-0 at Watford, Yeovil slipped closer to relegation with a 3-2 loss at Charlton, Nottingham Forest drew 3-3 with Sheffield Wednesday and Bolton won 2-1 at Doncaster.