A goal from Henrik Pedersen six minutes from the end of extra time took Bolton into the semi-finals of the Carling Cup at the Reebok Stadium last night after Antti Niemi had defied them throughout the regulation 90.
The Finnish goalkeeper made a string of magnificent saves but could do nothing when Youri Djorkaeff took a corner as penalties began to loom. When it cleared the goalmouth, another substitute, Anthony Barness, was there to drive it back and Pederson got the final touch.
Even then, Southampton almost equalised when Paul Telfer's rasping effort from well outside the area hit the bar, but there was no disputing that the Wanderers were full value for their belated win.
It was perhaps to be expected that this would take time to sort out. There are only a couple of points separating the sides in the Premiership table, both had morale-boosting away victories on Saturday and their last five meetings had all ended in draws.
Their previous 180 minutes against each other had failed to produce a goal, but it was entirely down to Niemi that further minutes were added to that tally. His heroics began as early as the second minute when he made a wonderful double save from Pedersen, the man who was destined to win the tie almost two hours later. First he made an acrobatic block when the Dane got his head to an inviting cross from Nicky Hunt and then he recovered quickly to get in the way of his follow-up shot.
Bolton, with Jay-Jay Okocha, Ibrahim Ba and Ivan Campo in charge of midfield, looked capable of creating chance after chance. They have had the good news this week that Okocha will not have to leave them for African Nations Cup preparation with Nigeria until January and his importance to the team was there for all to see last night.
It took another marvellous save from Niemi to keep out his free-kick and Okocha was also involved in setting up a series of other chances to keep the Southampton defence busy.
Kevin Poole, in goal in place of Niemi's Finnish rival, Jussi Jaaskelainen, had by contrast just once save to make, catching a shot from Telfer that came through a crowd of players.
Bolton should have had a penalty when Pederson was brought down by Jason Dodd and their frustration was growing by half-time, when Southampton's Ecuadorean, Agustin Delgado gave them a warning about the dangers of not killing off the opposition with a back-heel that skimmed the wrong side of the post.
The Wanderers had their only real stint of defending at the start of the second half and did not look particularly comfortable in that role. They burst out, however, in a flurry of activity that would have settled the issue there and then, if it had not been for the inspired Niemi.
Pederson and Okocha both shot wide after surging runs on goal, before Niemi leapt to tip over a shot from Hunt and then showed lightning reflexes to deny Okocha yet again.
Another delightful Okocha run forced yet another save from the overworked Finn before he got down at the feet of Bruno N'Gotty to save the day once more.
Bolton's Carling Cup specialist, Mario Jardel, had a chance to win it when he came on but shot straight at a goalkeeper who was not going to be beaten that easily, but Southampton could have snatched it against the run of play if Ricardo Gardner had not cleared off the line from Rory Delap, who fired a second effort wide as normal time ran out.
Jardel headed wide in extra time before Bolton finally had the ball in the net through Djorkaeff, but the flag had already been raised for off-side.
At last, after 284 goalless minutes between the two sides, Djorkaeff and Barness did their work and Pedersen, whose late intervention brought Bolton victory at Chelsea on Saturday, got the most significant if not the most calculated touch of the night.
Bolton have fielded some strange-looking sides in the Carling Cup this season. But it is a fair bet that they will take the competition absolutely seriously from now on and will not meet a more defiant goalkeeper than Niemi whoever they face in the semi-finals.
Bolton Wanderers: (4-4-2): Poole; Hunt (Barness, 110) N'Gotty, Charlton, Gardner; Ba, Campo, Okocha, Stelios (Djorkaeff, 90); Davies (Jardel, 77), Pedersen. Substitutes not used: Jaaskelainen (gk), Nolan.
Southampton (4-4-2): Niemi; Dodd, Svensson, Hall, Higginbotham; Telfer, Prutton, Delap, Pahars (McCann, 68); Ormerod, Delgado (Marsden, 65). Substitutes not used: Jones (gk),Kenton, Fernandes.
Referee: P Dowd (Staffordshire).