Son Heung-min’s peach of an opener that broke the deadlock here was regaled with the following: “Nice one Sonny, let’s have another one.” The ditty came from the 5,500-plus travelling Tottenham fans who saw their beloved No 7 ace a 25-yard finish past Preston’s goalkeeper Freddie Woodman as if coolly hitting down a first-serve winner. Cue Son greeting supporters with the cupped-hands-around-eyes “mask” celebration as this tie finally awoke. The strike came on 50 minutes, which gave Preston 40 more to try to force an equaliser or better, and they pressed. Instantly a corner was claimed but Ali McCann’s delivery disappointed. Next, Tom Cannon broke and tried to feed his forward partner, Ched Evans. Spurs conceded a throw-in and at this Ben Whiteman skipped across Tottenham’s D and unloaded but Fraser Forster watched the ball skid to safety. What occurred next was Son answering the Spurs faithful’s plea for “another one”. It was a near-carbon copy of his opener in precision and ruthlessness and this time beat Woodman to his left. The 30-year-old said: “I needed the goals for my confidence and just for playing games. They’re the positions I like to shoot from and in the first half I had two chances but the goalkeeper made good saves. I’m very, very happy. “It’s always hard in the FA Cup, especially when you play away from home. In the first half we struggled a little bit because they were defending really, really deep. I’m glad I could help the team and we can now look forward to the next round.” Just before the end, Arnaut Danjuma, on the pitch two days after joining on loan from Villarreal, sealed victory with a simple steer beyond Woodman from close to the penalty spot. Until Son’s first Spurs had been toothless on a dank evening in Lancashire. Devotees of the north London club packed out their end and a carnival atmosphere was heightened by pre-tie tunes from Elvis and Depeche Mode but what followed tempered the excitement. Tottenham, whose colours were last attached to this cup in 1991, had Rodrigo Bentancur padding about and stroking the ball around as Dejan Kulusevski, Yves Bissouma, Clément Lenglet and Japhet Tanganga all showed in a shape that featured Ivan Perisic as Antonio Conte’s nominated No 9. The Italian made seven changes, of which one was Harry Kane, who dropped to the bench as the captain waited to score his 267th goal for Spurs and move past Jimmy Greaves as the club’s record scorer. A Deepdale roar went up when Evans broke down the left, halted, shimmied and passed inside to McCann. The move faltered but this was followed by a Liam Lindsay nod down from a free-kick and the unmarked Andrew Hughes had a shot blocked. To enjoy the magic of the Cup, half-chances like these have to be finished. Son began with only six all season and surely thought he had secured his seventh when he let fly from long range, but Woodman tipped away. Robbie Brady was Preston’s next defender, planting his body in the way of a free-kick from the South Korean. A corner and a ballooned attempt from Kulusevski followed as the soporific fare continued. Kane, who had been ill, remained in his tracksuit when the sides switched ends. Spurs required his – or anyone’s – potency in front of goal. Kulusevski twirled and tapped to Perisic in Preston’s area, but his lack of centre-forward sharpness had the ball bouncing off him. But now Son took over and expertly showed how to hit the net. Both of his finishes followed a devilish parabola, came with a sweet swish of a boot and put Tottenham firmly en route to Monday’s draw. Ryan Lowe, Preston’s manager, said: “I’m immensely proud of my team – in the first half we were excellent. The fans were fantastic – they’ve been immense. With the first two goals we’d have obviously liked to get closer to [Son], but they were top finishes. We could have done a little bit better with the ball, but we were fantastic without it. There’s no disgrace in getting beaten by a team like that.”