Match ends, Newcastle United 2, Leicester City 3.
Newcastle manager Rafael Benitez said his side must cut out the mistakes they are making "week in, week out" after a late own goal against Leicester extended their poor run of form.
Striker Ayoze Perez poked the ball into his own net in the 86th minute as he tried to prevent Shinji Okazaki scoring, giving Leicester a thrilling 3-2 victory at St James' Park.
Newcastle have taken just one point from their past seven matches, and the cushion between them and the relegation zone is just two points.
"These kind of mistakes, you cannot make in the Premier League," Benitez said.
"We have to learn and have more experience and manage it better.
"We have seen two or three situations with the same kind of goals. It is sometimes a lack of experience."
Leicester's win was their third in a row in the Premier League - a run that has taken them up to eighth in the table.
The Foxes had made a terrible start as their hosts - roared on by a vocal home crowd following pre-game celebrations to mark the club's 125th anniversary - took the lead in the sixth minute courtesy of Joselu's close-range finish.
The visitors rallied quickly and restored parity when Mikel Merino's loose pass gave them possession and began an attack that Riyad Mahrez ended with a superb 25-yard, left-footed drive into the top corner.
Demarai Gray put them in front after the break with a shot that found the net via a deflection off Florian Lejeune before Dwight Gayle levelled matters with a shot that came off Harry Maguire, but City would have the final word.
It was an excellent victory for Claude Puel's side, who have now earned 17 points from eight league games since Craig Shakespeare was sacked in October.
Defeat represents the first time Benitez - who has previously managed Liverpool and Chelsea - has suffered three straight Premier League home losses.
Leicester continue upward trajectory
When Puel was appointed by Leicester, the team were 14th in the Premier League with just two wins from nine games.
The Frenchman had his doubters, who pointed - somewhat unfairly - to the 2016-17 season he spent in charge of Southampton, who he led to an eighth-placed finish and the EFL Cup final, but was accused of producing uninspiring football.
City's seven games under him have yielded both points and goals, with their only defeat at the hands of league leaders Manchester City.
On Saturday they recovered from two setbacks - one early in the game, one late - and played the more cohesive, attacking football of the two sides en route to a reward they deserved for their 63% possession and greater number of efforts on goal.
In Mahrez, Gray and Jamie Vardy they have an incisive attacking trio who will trouble any defence in the league and one seemingly restored to their potent best by their new boss.
Mahrez has been directly involved in eight goals in 16 appearances in the Premier League this season (four goals and four assists), which is just one fewer than in 36 games last season, when he managed six goals and three assists.
Gray has netted three goals in seven Premier League appearances since Puel took charge, having scored just once in his first 50 games in the competition.
Vardy was unfortunate not to add to his tally - which now stands at seven goals in 14 league games - but it was he who provided the cross towards Okazaki that forced Perez into his game-deciding error.
"[We had a] fantastic, positive attitude," Puel said. "
"It is difficult. After a good first half our start to the second half was not enough. We came back with the second goal. It was a fantastic move and a fantastic goal. We deserved this result and now it is important to continue from this result.
"It is a fantastic feeling at the end with the third goal and we deserved it."
Anniversary woes for Newcastle
In their 125-year history - a milestone they reached this week and celebrated before kick-off on Saturday evening with some impressive stadium-wide flag-waving - Newcastle have experienced notable highs, most notably a hat-trick of FA Cups in the 1950s.
But if they are to avoid this season ending in another significant low they must arrest a run of form that has now seen them fail to win in seven top-flight games, since a 1-0 victory over Crystal Palace in October.
In his programme notes, Newcastle manager Benitez referred to this week's celebrations, calling on his players to "use all that positivity around the stadium and city to support the players and give us the best chance of getting three points".
They got off to the best possible start thanks to an incisive link-up between forwards Gayle and Joselu.
The latter has come in for some criticism from Newcastle fans as a result of his inconsistent form since joining from Stoke in the summer for £5m but he showed good awareness to hold his run, in order to collect Gayle's cut-back, and precision to slot home the game's opening goal from near the penalty spot.
After Mahrez and Gray had swung the game back in the visitors' favour during a lengthy period of away dominance, Newcastle demonstrated a fighting attitude to get back into the game.
However, for the third home game running they would have nothing to show for their efforts, with this defeat following on from the demoralising losses to Bournemouth and Watford.
Man of the match - Riyad Mahrez (Leicester)
Newcastle can't hold on to a lead - the stats you need to know
- Newcastle have dropped 11 points from winning positions in the Premier League this term; the most of any team in the competition.
- Rafa Benitez's side are winless in seven Premier League games (W0 D1 L6) and have conceded 15 goals across their last five matches in the competition (an average of three per game).
- Dwight Gayle has scored more than a quarter of Newcastle United's 101 league goals since the start of 2016-17 (26/101).
- Four of Riyad Mahrez's last seven goals in the Premier League have come from outside the box, including both of his last two.
- Mahrez has been directly involved in eight goals in 16 appearances in the Premier League this season (four goals and four assists); just one fewer than in 36 games last season (six goals and three assists).
- Demarai Gray has netted three goals in seven Premier League appearances since Claude Puel took charge, after scoring just once in his first 50 games in the competition.
- Joselu's fourth-minute goal was Newcastle's fastest in a Premier League game since Loic Remy's in November 2013 (second minute v Norwich).
Newcastle host Everton - managed by former boss Sam Allardyce - in the Premier League on Wednesday (19:45 GMT), while Leicester travel to Puel's former club Southampton at the same time.
- 20LejeuneBooked at 81mins
- 11RitchieSubstituted forAtsuat 64'minutes
- 14HaydenBooked at 75mins
- 7MurphySubstituted forPérezat 71'minutes
- 21JoseluSubstituted forMitrovicat 88'minutes
- 26MahrezSubstituted forFuchsat 89'minutes
- 7GrayBooked at 12minsSubstituted forOkazakiat 73'minutes
- 9VardySubstituted forUlloaat 90'minutes
- Neil Swarbrick
- Shots on Target
Second Half ends, Newcastle United 2, Leicester City 3.
Attempt blocked. Dwight Gayle (Newcastle United) left footed shot from outside the box is blocked.
Foul by Marc Albrighton (Leicester City).
Ayoze Pérez (Newcastle United) wins a free kick in the defensive half.
Corner, Leicester City. Conceded by Isaac Hayden.
Corner, Leicester City. Conceded by Isaac Hayden.
Substitution, Leicester City. Leonardo Ulloa replaces Jamie Vardy.
Offside, Newcastle United. Isaac Hayden tries a through ball, but DeAndre Yedlin is caught offside.
Foul by Christian Fuchs (Leicester City).
DeAndre Yedlin (Newcastle United) wins a free kick on the right wing.
Substitution, Leicester City. Christian Fuchs replaces Riyad Mahrez.
Substitution, Newcastle United. Aleksandar Mitrovic replaces Joselu.
Own Goal by Ayoze Pérez, Newcastle United. Newcastle United 2, Leicester City 3.
Corner, Leicester City. Conceded by Karl Darlow.
Riyad Mahrez (Leicester City) wins a free kick on the right wing.
Foul by Javier Manquillo (Newcastle United).
Attempt missed. Wilfred Ndidi (Leicester City) right footed shot from outside the box misses to the left following a set piece situation.
Shinji Okazaki (Leicester City) wins a free kick on the left wing.
Foul by Mikel Merino (Newcastle United).