The Rams, who are still trying to forget their Wembley heartache from May, played host to Rotherham United as they looked to start their new Championship campaign with three points to avoid the inevitable 'play-off hangover' questions.
Both sides were not only under the spotlight because of their indifferent experiences at Wembley in May, but because it had a potential head-to-head with two youngsters on loan from arguably two of the best clubs in the world, Chelsea and Real Madrid.
Although neither started, which given their signings coming in the last week of pre-season is no surprise, they spent the last 24 minutes of the match with the chance to shine, as Swift came on for Rotherham to spark the attack and Mascarell came on for Derby to play in the holding midfield role.
Mascarell, who came on for Will Hughes, has played first team football for Real Madrid in the past and is thought to be one of the Champions League winner's most exciting prospects, and it was easy to see why.
He sat deep in the Derby midfield and despite not having much time to train with his new team mates, he looked assured and confident at all times. The young midfielder's ability to win and spread the ball was instantaneously evident as he was able to give the Rams an extra dimension.
In 36 minutes on the pitch, the Madrid starlet had 43 touches which made him one of the most active players in the game. He also made a total of 37 passes, which included seven accurate long balls from 11 attempts, and 2 clearances to help ensure the Rams of their win.
Swift, who did trouble Derby with his quality, was arguably Rotherham's best player on the day despite only playing just over 20 minutes.
The highly-rated Chelsea star, who won the man of the match award versus Leicester in Rotherham's last pre-season friendly, put fans on the edge of their seat as soon as he walked on to the pitch and his diagonal and direct runs at the Derby defence were certainly unnerving for Rams fans to see.
The midfielder, who came on in a wide attacking role, seemed to spark Rotherham into life going forward but unfortunately could only watch as the Rams, who had controlled the ball for large periods of the game, hit them on the counter attack and score the only goal of the game.
Nevertheless, the 19-year-old's impact wouldn't have gone unnoticed and Rotherham's next game, in the League Cup against Fleetwood, should see him on from the start as he looks for longer chance to make more of an impact.