Liverpool beaten by lowly Newcastle
All that Liverpool could point to after a disappointing display was a wrongly-disallowed goal by full-back Alberto Moreno that would have brought them an equaliser 10 minutes from the end.
Juergen Klopp's side remain seventh, six points behind the Champions League places, after only their second defeat in the 12 games since the German took took over from Brendan Rodgers in October.
Newcastle manager Steve McClaren had wanted his team to "get back to the basics of work-rate and organisation" and they did so to good effect in matching Liverpool's pressing game.
Newcastle took the lead after 69 minutes when Moussa Sissoko's cross was slightly mis-controlled by Wijnaldum but he still managed to fire in a shot that Skrtel deflected in.
Klopp had been dissatisfied enough to make a double change with an hour played, sending on Daniel Sturridge and fellow England international Adam Lallana for Benteke and the equally ineffective Roberto Firmino.
The two substitutes were involved in a rare scoring opportunity but Sturridge pulled his shot carelessly wide.
And Wijnaldum made sure of the points whe he clipped Sissoko's perfect through ball over keeper Simon Mignolet.