Sheffield United's Mark McNulty second half effort stunned Southampton, as the League One side defeated opponents that were placed exactly two divisions above them.

The result from Tuesday night epitomised Sheffield United's recent record against teams in Premier League in cups, as they have recently knocked out Aston Villa, West Ham and now Southampton. The Blades are building somewhat of a reputation of giant-killers in cup competitions; they have a fantastic record of only 2 losses in the last 18 cup games.

The Saints, who had put out a second string side, struggled on the night.

This is the fifth straight defeat for Southampton, and they are slowly starting to lose confidence after their best start to a top-flight season ever.

Southampton managed to create a chance out of nothing for Irish international Shane Long on the stroke of half-time; on the counter-attack he burst into the area but Sadio Mane, the Senegalese forward, dragged his shot wide after pressure from the defender, in what was probably the best chance of the half for the Saints.

Sheffield showed belief in the second half and continued to take the game to the opposition, which eventually led to the goal that won the game.

Mane, who was Southampton's summer signing from Salzburg, came close to score but shot wide; the punishment followed shortly when Blades scored in the 63rd minute, which was a tap-in from McNulty after Fraser Forster spilled an effort from a fiercely struck free-kick.

This came as a shock to Southampton and they were unable to get a foothold back in the game. It looked as though the League One outfit were going to add another goal, as Forster again had to make a good save to keep them in the game.

It was sending off in the 90th minute of the Southampton summer signing Florin Gardos, Romanian international from Steuea Bucharest that effectively killed off Southampton's hopes for an equaliser.

The Blades will be joining Chelsea in the draw for the semi-finals. The Blues defeated Derby 3-1 at Pride Park.