Match ends, Newcastle United 2, Cardiff City 1.
Newcastle earned a seventh consecutive league win as they beat Cardiff to strengthen their position at the top of the Championship.
Slack defending allowed Christian Atsu to give Newcastle an early lead, and Yoan Gouffran struck a second shortly before half-time.
Cardiff sparked hopes of a comeback when substitute Peter Whittingham scored with 13 minutes left.
But the hosts held on, meaning Cardiff remain 21st.
Second-placed Brighton cut Newcastle's lead at the summit from six points back down to three with a 2-0 win at Bristol City.
Whatever the outcome at Ashton Gate, Newcastle kept the pressure on their rivals with a rampant start against Cardiff.
They were ahead after less than three minutes as Aleksandar Mitrovic found space in the Cardiff penalty area before teeing up Atsu.
Rafael Benitez's men had chances to extend their advantage but Jonjo Shelvey's shot was blocked by Sol Bamba, while Cardiff goalkeeper Ben Amos denied Paul Dummett.
However, that was simply delaying the inevitable as, moments before half-time, Gouffran's low drive gave Newcastle the two-goal advantage their domination warranted.
Cardiff had chances to cut their deficit, with Craig Noone, Rickie Lambert and Bamba all failing to hit the target from promising positions.
Neil Warnock's side eventually struck courtesy of Whittingham's shot from the edge of the area, but their late efforts to rescue a point were in vain.
Newcastle manager Rafa Benitez: "We started well, had chances and scored two, and started the second half well, but we didn't do it.
"I would rather play passing football, getting goals. In football if you play well you will have chances to win games. Sometimes you can't because the opposition is aggressive and the ref allows this contact.
"If you can it means you are strong as well. Sometimes you play passing football, sometimes you have to be strong and defend and stand up."
Cardiff manager Neil Warnock: "I am so gutted at the penalty. Mitrovic mauls him down; at this level the officials should be educated better and know about the pull.
"To add salt the linesman gives the free-kick to them. They will go home and see it with their coaches next week and say 'oh yeah, I made a mistake'.
"We have not got enough goals in the squad at the moment - we have to work on that.
"There were some pluses though: the lads at the back especially. At half time they might have got five or six. The second goal killed us."
- 30AtsuSubstituted forDiaméat 89'minutes
- 20GouffranSubstituted forAnitaat 72'minutes
- 11NooneSubstituted forK Harrisat 75'minutes
- 15RichardsonSubstituted forWhittinghamat 74'minutes
- 17GunnarssonBooked at 85mins
- 19LambertSubstituted forChamakhat 72'minutes
- 5Ecuele Manga
- 24K Harris
- Tony Harrington
- Shots on Target
Second Half ends, Newcastle United 2, Cardiff City 1.
Ciaran Clark (Newcastle United) wins a free kick in the defensive half.
Foul by Marouane Chamakh (Cardiff City).
Attempt missed. Junior Hoilett (Cardiff City) right footed shot from the right side of the six yard box is too high. Assisted by Sean Morrison with a headed pass.
Foul by Mohamed Diamé (Newcastle United).
Kadeem Harris (Cardiff City) wins a free kick in the defensive half.
Substitution, Newcastle United. Mohamed Diamé replaces Christian Atsu.
Corner, Newcastle United. Conceded by Junior Hoilett.
Attempt saved. Sean Morrison (Cardiff City) header from the centre of the box is saved in the centre of the goal. Assisted by Ben Amos.
Foul by DeAndre Yedlin (Newcastle United).
Joe Bennett (Cardiff City) wins a free kick in the defensive half.
Aron Gunnarsson (Cardiff City) is shown the yellow card.
Ayoze Pérez (Newcastle United) wins a free kick in the defensive half.
Foul by Aron Gunnarsson (Cardiff City).
Aleksandar Mitrovic (Newcastle United) wins a free kick in the defensive half.
Foul by Sean Morrison (Cardiff City).
Foul by Ayoze Pérez (Newcastle United).
Aron Gunnarsson (Cardiff City) wins a free kick in the defensive half.
Goal! Newcastle United 2, Cardiff City 1. Peter Whittingham (Cardiff City) left footed shot from outside the box to the bottom right corner. Assisted by Marouane Chamakh.