This season it has felt like every away game is a cup tie.
Home support has been boosted by the draw of the Black Cats and the atmosphere has invariably been fevered.
In response, the opposition have found an extra gear.
So Sunderland would not have been surprised by the difficulties they faced against Neil Aspin's Port Vale.
The Black Cats looked set to blow them away in a superb opening half an hour, but the hosts battled back and will feel they should forced a replay.
The final whistle was greeted with relief by the travelling support, a fair indication of a testing second half.
Sunderland, though, are in the hat for the second round and have now made it seven consecutive wins in all competitions.
Jack Ross had set his stall out by naming a very strong XI for the game, and his players responded by scoring within 40 seconds. Port Vale switched off as Adam Matthews looked for Jerome Sinclair with a throw-in. Sinclair won the loose ball and Chris Maguire was able to tee up George Honeyman, who scored with an excellent curling finish.
Sunderland continued to press and a sizeable home support quickly came restless. Tom Flanagan blazed over from a promising position on the edge of the area after a corner fell kindly, while Chris Maguire and Aiden McGeady both threatened from range.
The second goal came 20 minutes in after another good move from the visitors.
Dylan McGeouch found Sinclair in the box, who did superbly to hold the ball under pressure from the Vale defence. His pass found Lynden Gooch, who finished well on the turn.
Aspin's side were rocking and for a short while at least, it looked as if the Black Cats would run rampant. But Chris Maguire twice overhit a simple pass from the right channel, Sinclair waiting in space to convert what would have been a straightforward finish.
An injury forced Aspin to reshuffle, and substitute Manny Oyeleke helped to turn the tide almost instantly. He wriggled free and played in Tom Pope, who scored with an excellent finish.
Sunderland came close to a third just before the break when a sweeping passing move found Gooch on the edge of the box. His half-volley was sweet but flew wide.
Buoyed by their rally towards the end of that first half, Port Vale began the second brightly and put the visitors under pressure with a succession of corners and throw ins.
They spurned a big opportunity to level when Ben Whitfield broke into the box from the left, the midfielder firing into the side netting.
Arguably the game's pivotal moment came when Luke Hannant got free in the box. Jack Baldwin went for the last ditch challenge, Hannant going to ground and Vale adamant that a penalty should have been given. Referee Anthony Backhouse waved play on and Sunderland were able to clear their lines.
The Black Cats were struggling to impose their game, forcing Ross to bolster his midfield with the introduction of Max Power.
That pushed Honeyman slightly further up the pitch and almost sprung a goal on the counter, finding McGeady with a good through ball. The Irishman took his shot early but couldn't beat Brown in the Vale goal.
By now the game was swinging from end to end, a fourth goal seemingly certain. McGeady and Honeyman combined again when the winger spun away from his marker on the left flank, getting to the byline and crossing. It took an outstanding from Brown to prevent Honeyman doubling his tally.
At the other end, the Black Cats were indebted to Reece James, who made an outstanding block to prevent a goalmouth scramble turning into an equaliser.
From there Vale lost some of their attacking momentum and Sunderland were able to see the game out.
Sunderland XI: McLaughlin; Matthews, Baldwin, Flanagan, James; McGeouch, Honeyman; Gooch (O'Nien, 80), Maguire, (Power, 70) McGeady; Sinclair (Maja, 64)
Subs: Oviedo, Loovens, Ozturk, Ruiter
Port Vale XI: Brown; Rawlinson, Smith, Legge, Vassell (Oyeleke, 30), Clark; Whitfield (Miller, 80), Conlon (Montano, 70), Hannant, Joyce; Pope
Subs: Kay, Hornby, Dodds, Hardcastle Bookings: McGeady, 48
Attendance: 7,238 (1,615 away)