The Rams goalkeeper made a string of superb saves to prevent the visitors from claiming all three points.
A different story looked set to unfold when Theo Robinson handed the hosts an early lead, but Southampton levelled through striker Rickie Lambert and went on to control the majority of the play.
Nigel Clough's side, looking to bounce back from a 4-0 hammering at the hands of Leicester before the international break, burst out of the blocks and went ahead with just three minutes on the clock.
Ben Davies rifled in a shot which Saints goalkeeper Kelvin Davis could only parry and Robinson was on hand to tuck home his third goal of the season from close range.
The shell-shocked Saints tried to respond through Richard Chaplow but the midfielder's strike from the edge of the box rolled tamely through to Fielding.
Guly Do Prado went close moments later with a first-time effort that flew narrowly over the bar.
Nigel Adkins' side started to pass the ball with confidence and earned a corner after 20 minutes which caused problems before Fielding eventually claimed.
Do Prado threatened again around the half-hour mark but Fielding came to the Rams rescue once more with a smart stop. Even when the County keeper was beaten by Jose Fonte's header just before the break, Steve Davies was in place to clear from underneath his own bar.
The visitors continued to push forward after the interval and Lambert tested Fielding once more with a stinging 18-yard drive which the shotstopper did well to handle.
But their pressure told after 61 minutes when Lambert collected a pass from David Connolly and lashed a low shot into the bottom corner from the edge of the box.
With the wind in their sails, Southampton pressed again as Connolly's teasing cross forced Jason Shackell to clear behind for a corner. Daniel Fox whipped in the delivery from the right and the unmarked Fonte nodded wide from 12 yards.
Derby slowly regained a foothold in the game and in the 70th minute Gareth Roberts delivered a teasing cross but Robinson could not force the ball past Davis.
There was concern when Steve Davies went down injured in the closing stages and he was carried off on a stretcher to be replaced by Tomasz Cywka.
Once play resumed it was Clough's side who went on the front foot as Mark O'Brien's header was well held by Davis.
In the seven minutes of time added on Jamie Ward appealed forlornly for a penalty but referee Mark Brown remained unmoved and his next significant action was to blow the full-time whistle.