Lee Bowyer and Shola Ameobi scored the goals which ensured Newcastle avoided a potentially embarrassing pitfall against non-league Yeading.
Yeading held out for 50 minutes before Ameobi and Craig Bellamy opened up Yeading's stubborn defence to provide Bowyer with a simple tap-in.
Ameobi clinched victory with a firm header from a free-kick.
Although Newcastle finished comfortable winners, David Clarke's free-kick forced a fine save from Steve Harper.
Despite a difference of 123 league places, Yeading showed scant respect for their Premiership opponents and in the opening exchanges were determined to test out Newcastle's new £8m signing Jean-Alain Boumsoung.
The French defender twice conceded free-kicks in dangerous positions and from the second for a foul on Errol Telemaque, Newcastle's defence was flat-footed as Emond Protain rose highest to head over.
DJ Campbell (left) and Bradley Quamina could not find the net
Newcastle tried to draw Yeading's sting by patiently stringing passes together and Ameobi worked his way to the by-line where his pull-back was met by a stretching Bowyer who deflected the ball wide from three yards out.
Yeading escaped on 19 minutes when Ameobi slid a pass through for Bellamy to rattle the crossbar with a ferocious shot, and as Newcastle maintained the pressure Delroy Preddie produced a brilliant fingertip save from Jermain Jenas' piledriver.
But at the other end, Newcastle keeper Steve Harper had to be at his best to prevent the Ryman League leaders from taking the lead.
Bowyer's rash challenge on Telemaque 20 yards out gave David Clarke the chance to curl a free-kick round the wall and it needed a full-length save from Harper to keep it out.
Another free-kick gave Yeading a chance at the start of the second half but from a training ground routine the ball was worked to Clarke whose shot curled wide from 22 yards.
But five minutes into the second half, the sighs of relief were audible as Newcastle took the lead.
Ameobi's pass found Bellamy scuttling into the inside-right channel and he placed the ball across goal to provide Bowyer with the simplest of tap-ins.
Bowyer had a chance to kill the game but lifted the ball over keeper Preddie and the crossbar as he burst on to Robert's cross.
Ameobi did give Newcastle breathing space just after the hour when he got ahead of his marker to plant a firm header past Preddie.
Relieved of the tension, Newcastle were able to play with some freedom and Bellamy led a lightning break from defence which ended with Bowyer firing over under pressure from Clarke.
Newcastle attacked in waves as the part-timers tired, but they refused to fold and showed determination and spirit to deny Newcastle.
Yeading were denied a deserved consolation when Harper went full-length to palm away Darti Brown's fierce shot.
Yeading: Preddie, Nevin Saroya, Marc Leach, Stanley,Barima (Behzadi 74), Haule, Darti Brown, Clarke,Protain (Woodruffe 78), Telemaque (Quamina 84), DJ Campbell.
Subs Not Used: Newby, Kleboe.
Newcastle: Harper, Taylor, Boumsong,Bramble (Andrew O'Brien 45), Babayaro, N'Zogbia (Ambrose 39),Jenas, Bowyer, Robert (Milner 70), Bellamy, Ameobi.
Subs Not Used: Given, Hughes.
Goals: Bowyer 51, Ameobi 61.
Referee: H Webb (S Yorkshire).