A Mike Williamson own goal handed Championship side Brighton a place in the FA Cup fifth round at the expense of Premier League Newcastle.
Will Buckley's 76th-minute shot struck the defender and looped over the helpless Tim Krul.
Newcastle wasted good chances, Leon Best twice firing just off target when well placed and having another shot saved by Peter Brezovan.
Yohann Cabaye had a shot charged down as Newcastle sought a late equaliser.
With Newcastle's Senegal strikers Demba Ba and Papiss Demba Cisse due to make early returns from the Africa Cup of Nations, Best and Shola Ameobi were keen to make an impression up front.
Best almost made a perfect start when he found space on the edge of the box and his low drive flew narrowly wide.
He wasted an even better chance in the 12th minute when Ameobi picked out Best, who headed over from six yards.
The best opportunity of the first half fell to full-back Danny Simpson. He stormed into the box to latch on to Hatem Ben Arfa's clever pass but stabbed his shot into the chest of Brezovan.
The Seagulls rarely threatened, although lively winger Buckley gave Italian defender Davide Santon a difficult time.
The second half started in a similar vein with Ameobi rolling the ball to Best, whose his angled shot struck Brezovan's legs. From the resulting corner, Ameobi's 10-yard strike was deflected just wide.
Newcastle became increasingly frustrated and tempers began to fray with Cabaye kicking out in a challenge with Adam El-Abd and appearing to catch the Brighton defender in the face.
El-Abd had been involved in a heated row with Best, which was then mirrored on the touchline when Brighton assistant Mauricio Taricco and Jon Carver, his opposite number at Newcastle, had a lively conversation after Simpson was booked for a strong tackle.
Krul was finally called into serious action in the 70th minute when he dived full length to keep out Craig Mackail-Smith's 20-yard strike.
But six minutes later he was beaten. Buckley jinked into the penalty area with a clever step-over and hit a left-footed shot which was diverted past Krul by Williamson.
Newcastle manager Alan Pardew made a triple substitution as he tried to salvage a replay.
The closest the visitors came was a Cabaye shot from the edge of the box that was blocked by Ashley Barnes. Newcastle's appeals for hand ball were waved away.