If only Sunderland could transfer their cup form to the Premier League, Gus Poyet's side would probably be pushing for Europe rather than striving to stay out of the Championship.
With Poyet having made nine changes to a team battling relegation and already in the League Cup final, the stage looked set for Southampton to canter into the quarter-final. Inexplicably, given their comfortable league position, Mauricio Pochettino made six changes and, significantly, a strange performance from his players fell some way short of high-octane.
Sunderland played quite well but, by semi surrendering, Southampton effectively ushered them towards both the sixth round and mounting fixture congestion.
Evidently not entirely heartbroken to lose, Pochettino was so eager to head for Newcastle airport and a return flight south that he did not bother addressing the media afterwards. "We're not disappointed to be out of the FA Cup," said Jesus Perez, his assistant before, hastily, adding the rider, "Just a little bit sad."
Poyet experimented with fielding two up front rather than a lone striker and will not be afraid to reprise his 4-1-3-2 formation. "I think I'll call every game a cup game from now on," he joked. "It's been a good day, we cared about the ball and a few players put themselves back in the frame."
For Lee Cattermole, a recall offered a chance to try to reclaim his Premier League place from the rested Liam Bridcutt. His effectiveness was such that Oscar Ustari, Poyet's Argentinian goalkeeper, rarely needed to make serious saves.
Despite some very decent cameos from the classy Emmanuele Giaccherini, Sunderland struggled to fully stretch the sporadically shaky Kelvin Davis.
True, Poyet's players won several free-kicks in dangerous positions but their execution too often proved wayward. Meanwhile, Ignacio Scocco, the Argentina striker making his debut alongside the intelligent Fabio Borini in the home attack, showed off some lovely touches but appeared to be finding the intensity of it all something of a culture shock after leaving Brazilian football behind last month.
Played in pouring rain and with a crowd of under 17,000 leaving large banks of empty red seats inside the stadium it was turning into a slightly sorry spectacle but at least Craig Gardner's right foot finally raised the tone.
Long-range shooting is very much Gardner's party trick and, after beating Victor Wanyama – searching for form and fitness after a lengthy period out injured – to the ball in the 49th minute, he unleashed a 20-yard shot which arched imperiously before brushing the underside of the bar en route to the top corner, leaving Davis scratching thin air.
Gardner's touch may not always be exactly velvet but his well-timed runs from midfield frequently took him behind Pochettino's defence, contributing to increasing visiting discomfort. Even so the game remained sufficiently open for Southampton to very nearly draw level when the influential Adam Lallana – subsequently, inexplicably, withdrawn – connected with Nathaniel Clyne's cross only for his flick to fly wide.
An unwanted replay averted, Pochettino quite possibly stifled a sigh of relief.