Newcastle striker Perez netted in the 27th and 31st minutes and added a late clincher four minutes from time to move to 10 top-flight goals for the season.

Substitute Mario Lemina's first league goal in 14 months, combined with injuries to Miguel Almiron and Fabian Schar, made for a tense second half for the hosts, but they prevailed to leave Southampton with work to do to secure its own survival.

Newcastle had an early penalty claim turned down when Almiron's shot was blocked by the hand of Pierre-Emile Hojbjerg at close range, before the Paraguay international had a blistering strike tipped over by Angus Gunn.

Home players were fuming with referee Anthony Taylor again when he only showed James Ward-Prowse a yellow card for bringing down Almiron near the halfway line as he raced towards goal, Rafael Benitez's assistant Mikel Antia sent to the stands for his protests.

But the mood at St James' Park improved rapidly when Perez struck twice in under four minutes. First, he showed strength to hold off Maya Yoshida and send a fine finish into the far corner after Isaac Hayden's tackle had set up the chance, before the Spaniard converted Salomon Rondon's precise cross with a sliding back-post finish from six yards.

Southampton brought on Lemina and Stuart Armstrong at half-time, but it was almost game over when Ki Sung-yueng fired a low strike against the foot of the post from almost 25 yards.

The visitors took advantage of that reprieve in the 59th minute, Lemina confidently finding the bottom corner from the edge of the box after being set up by Nathan Redmond and Armstrong.

Newcastle lost both a tearful Almiron and then Schar to injuries, and tensions were high when Yoshida blazed over a glorious chance to equalise from six yards.

Gunn then made a superb save from Hayden's deflected strike and Rondon's header was cleared off the line by Ward-Prowse, but a third goal arrived when Perez cleverly diverted Matt Ritchie's diving header past the keeper.