Monk's side dominated much of the proceedings in south Wales on Saturday, but a Papiss Cisse brace secured a 2-2 draw for struggling Newcastle.
The hosts started in commanding fashion and took an early advantage, Wilfried Bony notching his first of the season with a calm finish past Tim Krul after neat interplay with the impressive Gylfi Sigurdsson.
Cisse pulled it level for the visitors in the 42nd minute, but former Newcastle winger Wayne Routledge put Swansea back in front just after the interval with a sublime dink after also latching onto a Sigurdsson pass.
The Iceland midfielder now has a joint league-high six assists to his name, but it came in vain as Cisse once again hit back, converting Sammy Ameobi's cross to steal a share of the spoils.
Despite starting the season with three consecutive victories, Swansea are now without a success in four league games, and Monk insisted that sloppy defending was the root of their problems against Alan Pardew's men.
"I think it's two points dropped really," Monk told reporters after the final whistle.
"The goals we conceded were poor and it was a lack of concentration that has cost us dearly.
"We were dominant but conceded a poor goal just before half-time, but after we scored the second the possession became too easy.
"A lack of concentration cost us and they countered and scored the two chances that they had but overall, I think we should’ve won the game by at least a couple of goals.
"Their keeper made some great saves and we should've extended our lead but when you don't and you haven't quite put the game to bed then you always run the risk in this league of a team popping up with something out of nothing."
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