The Reds had not beaten the Blades on the road since 2004, but they have now broken that record to take a slim advantage back to the City Ground.
Here are some key talking points from the semi-final first leg.
Forest could have been out of sight in the first half
Within ten minutes, the Reds had taken the lead, but the first half could have finished with the away side home and dry.
After that, Foderingham came to the rescue once more, making a pair of close-range saves to keep Surridge and Brennan Johnson out.
Man of the match display from Steve Cook
Both Worrall and McKenna were outstanding, but Cook's defensive statistics against the Blades demonstrated how solid the defender was.
Cook kept United at bay for the bulk of the game with 11 clearances, three blocks, three tackles, and one interception, making it tough for Paul Heckingbottom's side to break through and get a chance on goal.
The 31-year-old won all three ground duels he attempted, as well as the one aerial duel he faced.
It was a gutsy and remarkable performance from the defender after suffering a head injury against Bournemouth and learning that his father had recently suffered a cardiac arrest.
Hardworking Sam Surridge
Since joining Nottingham Forest in January, the 23-year-old has been recognised for his goal involvements, but he demonstrated his quality in all areas of the pitch during this game.
Surridge had to help in all areas of the pitch as he continued to be a part of most of Forest's forward threat with two shots on target, two critical passes, and 100 percent dribble succession.
The striker was perfectly situated to make a clearance off the line early in the first half, keeping his team in front. In addition, the forward won three ground duels, one aerial duel, and blocked one shot.
Surridge's press kept Blades defenders on their toes, and while not scoring a goal during the match, he was highly involved in it and led the line well from the front.
Up next: The second leg
Tuesday's second leg promises to be exciting, with Forest in the lead. The game ended 1-1 the last time Forest hosted Sheffield United at the City Ground, a result that would see the Reds progress to the final on Tuesday.
After Saturday's game, Steve Cooper expressed his gratitude to the local media for the victory but emphasised the importance of continuing on Tuesday.
“I’m really, really pleased. We have to keep going.
“I got asked before the game what a good result would be - we wanted to win. I know a draw isn’t a disaster, and even a narrow loss is not the end of the world either. I understand that, but we have tackled and challenged everything in front of us head-on, so let’s not change now. Let’s play the way we play; work the way we work and see where it takes us.”