Newcastle made heavy weather of beating Zulte-Waregem to secure their passage to the last 16 of the Uefa Cup.
Damien Duff created Martins' goal
Obafemi Martins scored the second-leg winner, delicately lifting the ball over keeper Sammy Bossut to give the Magpies a 4-1 win on aggregate.
Newcastle, who will now meet AZ Alkmaar, had failed to force Bossut to make a serious save prior to the goal.
The Belgian side threatened in the first half but Titus Bramble and Steven Taylor thwarted their attacks.
Arguably Waregem had suffered stage fright in the first leg but there were no nerves on show at James' Park, with Stijn Meert orchestrating the visitors' attacks with some style.
Meert provided the pass of the game, releasing Sebastien Siani, only for Bramble to deliver the tackle of the game, sliding in to take the ball away from the Cameroonian striker.
Just before the interval Steven Taylor proved equally diligent in stopping Wouter Vandendriessche from shooting in a dangerous position, with another well-judged tackle.
606 DEBATE: Your reaction to Newcastle's victory
Taylor had had Newcastle's first chance of the game - a header that was cleared off the line by Meert.
James Milner was Newcastle's most effective player in those opening minutes, crossing for Albert Luque, who was unable to get a decisive touch on the ball.
Milner's next contribution was to shoot narrowly over the bar, while a Kieron Dyer effort proved too powerful for Bossut, who needed two attempts to get hold of the ball.
Newcastle's early momentum gradually dissipated as Meert took charge in midfield and Waregem visibly grew in confidence.
Early in the second half Vandendriessche had the honour of forcing the first save of the game as Steve Harper pushed away his swerving shot.
Bart Buysse missed a wonderful opportunity to put the visitors ahead when the Waregem defender connected with Tim Matthys' free-kick only to head wide.
Martins finally gave Newcastle's fans something to cheer about when he collected Duff's through pass before cleverly dinking the ball past Bossut and into the net.
Even then Newcastle failed to capitalise on the goal and in the closing stages Bramble capped an impressive performance when he threw himself at the ball to block a shot from Matthys.
Newcastle might have looked distinctly unimpressive for much of this game but their record in Europe this season is undoubtedly impressive - Glenn Roeder's side are now unbeaten in 12 games.
Newcastle: Harper, Taylor, Bramble, Babayaro (Huntington 46), Milner, Solano, Butt (Pattison 65), Dyer, Duff, Luque (Carroll 65), Martins.
Subs Not Used: Srnicek, O'Brien, Edgar, LuaLua.
Goals: Martins 68.
Zulte-Waregem: Bossut, Minne (Reina 76), D'Haene, Dindeleux, Buysse, Vandermarliere, Van Steenbrugge, Vannieuwenhuyse, Meert, Van Den Driessche (Sergeant 56), Siani (Matthys 56).
Subs Not Used: Merlier, Verschuere.
Ref: Nikolai Ivanov (Russia).