Southampton completed a dramatic final-day escape from relegation by coming from behind to beat the Blades.

Stern John cracked a second-half double and Marek Saganowski's header shortly before the interval ensured the Saints avoided the drop to League One.

The south coast side are well versed at beating relegation on the final day – in the Premier League they went into the last day of the season in danger of relegation four times during the 1990s.

But having dropped out of the top flight three years ago, they were staring down the barrel of third division football when Stephen Quinn put the Blades ahead.

Saganowski equalised and John fired Saints ahead at the start of a nerve-shredding second half, in which United substitute Jon Stead dragged his side level.

But John's 19th goal of the season, and comfortably the most important – means St Mary's will again be hosting Charlton, rather than Cheltenham, next term. The striker's afternoon ended prematurely as he was sent off for a second yellow card 10 minutes from time, but the 10 men held out.

The Blades fashioned the first chances, with Gary Speed seeing a header deflected over the top and Rob Hulse shooting high and wide.

The sell-out crowd began to find their voice as the hosts started to crank up the pressure, with a couple of crosses from Andrew Surman causing some angst in the United defence.

But Southampton were shoved closer to the drop in the 23rd minute when Billy Sharp curled in a deep cross from the right which the unmarked Quinn met with a firm header back across Richard Wright and into the net.

Saganowski twice came close to equalising, with a header which hit Matt Kilgallon and the point-blank drive blocked by Paddy Kenny. The Blades were only denied what could have been a killer second by a save by Wright from Kilgallon's header. And moments later St Mary's erupted when Jason Euell's swirling cross was converted by Saganowski at the far post. A re-energised Saints emerged after the break and six minutes into the second half John sparked delirium in the stands.

John fed Saganowski and continued his run into the area as the Pole deftly lofted the ball over Kilgannon and John Halls and back into his path.

St Mary's held its breath as John took an age to bring the ball down, eight yards out, before dispatching the ball.

The Blades would not lie down and substitute Stead levelled when he poked home Quinn's cross from close range.

But Saints were not to be denied and John was again the man in the right place, latching onto Jhon Viafara's header, turning inside the area and shooting low past the wrong-footed Kenny. He was dismissed with 10 minutes remaining for a foul on Derek Geary.

Southampton: Richard Wright, Jermaine Wright, Powell, Perry, Surman, Viafara, Safri, Idiakez (Licka 79), Euell, Saganowski (Lallana 73), John. Unused substitutes: Davis, Wright-Phillips, Pericard.

Sheffield United: Kenny, Geary, Kilgallon, Naysmith, Halls, Cotterill (Gillespie 38), Speed, Tonge, Quinn, Hulse (Stead 63), Sharp (Shelton 56). Unused substitutes: Bennett, Armstrong.

Referee: P Joslin (Notts).

Blades man of the match: Stephen Quinn.