Match ends, Newcastle United 0, Brighton and Hove Albion 1.
Rafael Benitez said turning around Newcastle's fortunes will be the toughest challenge of his career after slipping to the bottom of the Premier League following defeat by Brighton.
The Magpies remain winless after a fifth straight home loss thanks to Brighton's Beram Kayal, who deflected in Jose Izquierdo's strike in the 29th minute.
The Seagulls lost leading scorer Glenn Murray, who was taken off after a sickening aerial collision in the ninth minute.
Brighton boss Chris Hughton later stated that the forward had been concussed but would leave hospital after having precautionary scans.
But it did not put the visitors off their stride in a match where they spent most of the time defending.
Benitez said the Magpies needed to be "more precise and clinical" after producing 27 shots on goal, with only six on target.
Midfielder Jonjo Shelvey went closest to scoring - first with a strike that was superbly blocked by Mat Ryan, then with a free-kick saved by the Australian with the help from his wall.
And despite saying he was confident he could turn things around, when asked if the current situation is the toughest he has faced, the Spaniard said: "Yes, at the moment, yes.
"I have had a lot of situations, but at the moment, obviously it's a difficult task."
The result means Newcastle are the fourth team in top-flight history to lose their first five home games of a season - the other three teams were relegated.
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He led Liverpool to European glory and Valencia to two Spanish league titles, but can he stop Newcastle from falling through the Premier League trap door for a second successive season?
Newcastle's display at Old Trafford before the international break seemed to suggest that a turn in fortunes was just around the corner. But against Brighton, who came to the North East winless in 17 away league games, that cutting edge that almost saw off Manchester United was missing once more.
After going behind in the 29th minute, they continually pressed the visiting backline. But many of their efforts on target barely troubled Ryan, who was only really tested by Shelvey.
Scottish midfielder Matt Ritchie, with a header that flew narrowly wide, and Yoshinori Muto, nodding over a difficult chance, were the only other efforts of note from Newcastle.
An away trip to Southampton is next for the Magpies.
Brighton make the most of few chances
The mini-jinx is over. After four failed attempts, Hughton has finally won at St James' Park as a former manager thanks to a brilliant defensive display, led by Shane Duffy and Lewis Dunk, and Kayal's first-half strike.
The loss of Murray early in the match took the bite out of his side's attack, but they were less profligate than their opponents in front of goal and scored with the one shot on target from their seven efforts.
Kayal's name is on the scoresheet, but much of the credit for the goal goes to Colombian jack-in-the-box Izquierdo, whose shot from a corner took a slight deflection off the Israel international and beat keeper Martin Dubravka.
The Seagulls almost added another in the closing minutes, but substitute Yves Bissouma fired a foot wide after racing clear of the Newcastle defence.
He might be asked to do extra shooting practice in training, while his defence deserve an extra day off.
Man of the match - Shane Duffy (Brighton)
Newcastle travel to Southampton next Saturday, still looking for their first league win of the season, while Brighton host Wolves (both 15:00 BST).
- 13MutoSubstituted forJoseluat 74'minutes
- 2BrunoSubstituted forBernardoat 68'minutes
- 16JahanbakhshBooked at 74mins
- 7KayalBooked at 43mins
- 19IzquierdoSubstituted forBissoumaat 80'minutes
- 17MurraySubstituted forLocadiaat 16'minutes
- Andre Marriner
- Shots on Target
Second Half ends, Newcastle United 0, Brighton and Hove Albion 1.
Attempt saved. Jürgen Locadia (Brighton and Hove Albion) left footed shot from the centre of the box is saved in the bottom left corner. Assisted by Bernardo with a cross.
Attempt missed. Yves Bissouma (Brighton and Hove Albion) right footed shot from the centre of the box is close, but misses to the right. Assisted by Jürgen Locadia.
Attempt blocked. Kenedy (Newcastle United) left footed shot from outside the box is blocked.
Foul by Mohamed Diamé (Newcastle United).
Dale Stephens (Brighton and Hove Albion) wins a free kick in the defensive half.
DeAndre Yedlin (Newcastle United) wins a free kick in the defensive half.
Foul by Jürgen Locadia (Brighton and Hove Albion).
Mohamed Diamé (Newcastle United) wins a free kick in the attacking half.
Foul by Yves Bissouma (Brighton and Hove Albion).
Paul Dummett (Newcastle United) wins a free kick on the left wing.
Foul by Jürgen Locadia (Brighton and Hove Albion).
Attempt missed. Joselu (Newcastle United) right footed shot from outside the box misses to the right.
Offside, Newcastle United. Jonjo Shelvey tries a through ball, but Joselu is caught offside.
Substitution, Brighton and Hove Albion. Yves Bissouma replaces José Izquierdo.
Attempt saved. Kenedy (Newcastle United) left footed shot from outside the box is saved in the top centre of the goal.
Attempt blocked. Kenedy (Newcastle United) left footed shot from the left side of the box is blocked. Assisted by Ayoze Pérez.
Corner, Newcastle United. Conceded by Mat Ryan.
Attempt saved. Jonjo Shelvey (Newcastle United) right footed shot from outside the box is saved in the top centre of the goal.