Son found a way through in the final 10 minutes with a shot that proved too hot for Martin Dubravka to handle in the visiting goal.
Spurs had earlier hit the crossbar and also had an effort cleared off the line, while Newcastle came close through Solomon Rondon's header against the post.
Relive how the 90 minutes of action unfolded with Sports Mole's live text coverage below.
STARTING XI: Lloris; Trippier, Alderweireld, Sanchez, Vertonghen; Eriksen, Winks, Sissoko; Lamela, Son, Lucas
SUBS: Gazzaniga, Rose, Wanyama, Dier, Walker-Peters, Llorente, Foyth
STARTING XI: Dubravka; Yedlin, Lejeune, Schar, Lascelles, Ritchie; Perez, Hayden, Longstaff, Atsu; Rondon
SUBS: Woodman, Clark, Kenedy, Fernandez, Manquillo, Joselu, Barreca
TOTTENHAM SUBS: Gazzaniga, Rose, Wanyama, Dier, Walker-Peters, Llorente, Foyth
NEWCASTLE SUBS: Woodman, Clark, Kenedy, Fernandez, Manquillo, Joselu, Barreca