Match ends, Leicester City 1, Fulham 2.
Manager Scott Parker praised forward Ivan Cavaleiro's "courage" as his penalty helped Fulham climb out of the Premier League relegation places.
Parker's side had missed three penalties in a row before Cavaleiro converted to help secure victory at Leicester, who missed the chance to go level on points with leaders Tottenham.
The Portuguese had been one of the spot-kick culprits - missing in a 3-2 home defeat by Everton eight days earlier - and Parker was impressed with the way he stepped up.
Aleksandar Mitrovic had hit the bar with a penalty at Sheffield United in October, and Ademola Lookman had been widely criticised for a failed attempt at a Panenka-style spot-kick in the defeat by West Ham on 7 November.
"Lookman came under a lot of stick when he did the penalty and he needed to take his medicine," Parker said.
"Cavaleiro slipped last week and I'm not on Twitter or Instagram but I can only imagine what was being said, the jokes at his expense.
"I said to him: 'Are you ready to take one if we get it?' He looked at me dead in the eye and said: 'I'm ready.' It's the courage to step up there are the things we need."
Lookman scored Fulham's opener, slotting past Kasper Schmeichel following Andre-Frank Zambo Anguissa's driving run from inside his own half.
Cavaleiro stepped up to make it 2-0 before half-time, after referee Simon Hooper reviewed Christian Fuchs' tackle on Bobby Decordova-Reid on the pitchside monitor.
Leicester had earlier struck the woodwork twice in quick succession as Wesley Fofana's follow-up to Youri Tielemans' volley cannoned off the crossbar.
But the Foxes, as they did in their 3-0 defeat by Liverpool, endured another frustrating night in attack until substitute Harvey Barnes' late reply ensured a nervy finale for Fulham.
"Ade earned the right to score his goal and Cav put himself up to be scrutinised," Parker said. "There's no denying there's relief.
"We're in a world where it's win or lose for all of us and that's the big picture. I've spoken to them about not letting defeats cripple us."
Fulham's second win of the season takes them up two places to 17th, while Leicester remain fourth and three points behind leaders Tottenham.
RB Leipzig loanee Lookman celebrated his goal by holding up a Senegal shirt which had been hung in the visitors' dressing room, in tribute to former midfielder Papa Bouba Diop, who died aged 42 on Sunday.
Fulham show they are up for the fight
A match at the King Power Stadium marked the start of a difficult run of fixtures for Parker's side, with a trip to Manchester City and the visit of Liverpool to come. They meet five of the 'big six' in their next nine games.
Fulham arrived at Leicester on the back of successive defeats, with the league's joint-worst defensive record and only one win in 25 Premier League away matches.
But Parker called for greater intensity after his side let in three goals in their defeat by Everton - the fourth time they had conceded three or more in nine league games - and how his call was answered here.
The visitors appeared focused and well-organised from the off, while the return of Anguissa brought calm in midfield.
Anguissa's positive play and neat through-ball teed up Lookman's well-taken opener, while the mazy runs of the England youth international caused Leicester problems on the break throughout.
Cavaleiro's coolness from the spot, following his unfortunate slip in his previous miss, perhaps best typified a transformed Fulham display.
The visitors took a much more defensive approach in the second half in an attempt to keep Leicester at bay but, after Lookman was denied by Schmeichel at close range with 15 minutes remaining, Parker's men successfully endured a late barrage to leave with an excellent three points.
Below-par Leicester miss out
Brighton's injury-time equaliser against Liverpool and Tottenham's goalless draw with Chelsea over the weekend gave Leicester the chance to keep pace at the top and put a disappointing display at Anfield behind them.
However, a late flurry was not enough to undo the damage of an uninspiring first-half performance.
Rodgers' side had to wait until the 19th minute for their first attempts at goal, but Fofana lacked composure after he was fastest to react to Tielemans' sweetly hit volley from the edge of the penalty area.
Starved of supply against Liverpool, last season's Golden Boot winner Jamie Vardy struggled again against the Londoners, touching the ball only once in the first 25 minutes at the King Power Stadium.
Vardy, whose last-gasp equaliser against Braga on Thursday ensured qualification for the Europa League last 32 with two games to spare, produced a clever flick from Dennis Praet's cross to draw Alphonse Areola into action, but it was a rare opportunity for the hosts.
After Vardy's header set up Barnes, substitute Kelechi Iheanacho twice had a shot blocked in a desperate final push for an equaliser - but it is now successive league defeats for the Foxes.
'A big win' - what the managers said
Leicester manager Brendan Rodgers, speaking to Sky Sports: "It was a disappointing first half for us. We made mistakes in our defensive moments and in this league, if you give away opportunities, it can be very difficult.
"Fulham deserved to win - they punished us and we weren't good enough to break them down. We're a young side and we've had some very good performances. Evenings like this show the youthfulness of the team and we've still got work to do."
Fulham boss Scott Parker, speaking to Sky Sports: "I'm delighted with the team's efforts. With where we are, we're judged on our results. It was a battling display, some magnificent performances and some real quality as well.
"We're a little disappointed with the goal but in the second half, we knew we'd come under a bit of pressure but you've got to enjoy that. This is a big win for us. We need to keep pushing and we'll keep going in the right direction."
Fulham love Mondays - the stats
- Fulham beat a side starting the day in the top four of the Premier League for the first time since March 2013, having lost 14 of their past 15.
- Their two Premier League wins this season have both come on a Monday. In fact, the Cottagers have won five of their past seven top-flight games on a Monday.
- Fulham have lost just one of their seven Premier League games against Leicester.
- Leicester have lost consecutive Premier League games against sides starting the day in the relegation zone for the first time since November 2014.
- This was Foxes manager Brendan Rodgers' first managerial defeat against Fulham in the Premier League, after winning each of his previous seven.
- Ivan Cavaleiro became the first player to score a Premier League penalty for Fulham since Aleksandar Mitrovic against Leeds in September. The Londoners had missed each of their previous three in the competition.
Following their penultimate Europa League group game against Zorya Luhansk in Ukraine on Thursday (17:55 GMT), Leicester visit Sheffield United on Sunday (14:15).
Fulham have four days to regroup before they travel to Manchester City on Saturday afternoon (15:00).
- 24MendySubstituted forIheanachoat 70'minutes
- 33ThomasSubstituted forÜnderat 45'minutes
- 26PraetSubstituted forBarnesat 45'minutes
- 14De Cordova-Reid
- 16AdarabioyoBooked at 89mins
- 15Loftus-CheekSubstituted forLeminaat 77'minutes
- 21ReedBooked at 18mins
- 29Zambo Anguissa
- 19LookmanSubstituted forBryanat 90'minutes
- 17CavaleiroSubstituted forMitrovicat 86'minutes
- Simon Hooper
- Shots on Target
Second Half ends, Leicester City 1, Fulham 2.
Corner, Fulham. Conceded by Christian Fuchs.
Attempt blocked. Ola Aina (Fulham) left footed shot from outside the box is blocked. Assisted by Aleksandar Mitrovic.
Attempt blocked. Kelechi Iheanacho (Leicester City) left footed shot from the right side of the six yard box is blocked. Assisted by Cengiz Ünder.
Corner, Leicester City. Conceded by Tosin Adarabioyo.
Attempt missed. James Justin (Leicester City) right footed shot from outside the box is high and wide to the right following a corner.
Corner, Leicester City. Conceded by Ola Aina.
Attempt blocked. Kelechi Iheanacho (Leicester City) left footed shot from the centre of the box is blocked. Assisted by Harvey Barnes.
Substitution, Fulham. Joe Bryan replaces Ademola Lookman.
Foul by Jamie Vardy (Leicester City).
Tosin Adarabioyo (Fulham) wins a free kick in the attacking half.
Tosin Adarabioyo (Fulham) is shown the yellow card.
Foul by Wesley Fofana (Leicester City).
Aleksandar Mitrovic (Fulham) wins a free kick in the attacking half.
Attempt missed. James Maddison (Leicester City) right footed shot from outside the box is too high. Assisted by Christian Fuchs.
Substitution, Fulham. Aleksandar Mitrovic replaces Ivan Cavaleiro.
Goal! Leicester City 1, Fulham 2. Harvey Barnes (Leicester City) left footed shot from the centre of the box to the top left corner. Assisted by Jamie Vardy with a headed pass.
Attempt blocked. Cengiz Ünder (Leicester City) left footed shot from outside the box is blocked. Assisted by Youri Tielemans.
Corner, Leicester City. Conceded by Joachim Andersen.
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