Ole Gunnar Solskjaer’s team won either half-time, before Colin Kazim Richards scored one for Wayne Rooney's Championship side.
Tom Heaton impressed in his first appearance since joining the club again this summer, while Jesse Lingard looked sharp despite only being back to training last week after his loan spell at West Ham United.
Solskjaer had most of his stars away on holiday following Euro 2020. He chose a team that included both first-team regulars as well as youngsters to prepare for the new Premier League season.
Heaton, who was a free transfer from Aston Villa and has now returned to the club in goal, began behind a back four that included Brandon Williams, Aaron Wan-Bissaka and Axel Tuanzebe.
Juan Mata, the captain of the day, as well as Mason Greenwood, academy graduates Teden Mengi and Dylan Levitt were also included in the team, along with Chong, James Garner, Anthony Elanga and James Garner.
United took the lead in 18 minutes when Chong robbed Max Bird of the ball in the penalty area. He then scored at the second attempt, after his first attempt was saved by Kelle Roos, Derby goalkeeper.
Solskjaer made nine adjustments at half-time, with Tuanzebe (centre-back) and Mengi (center-backs) remaining in their respective places.
Lingard, Alex Telles and Nemanja Matic were just a few of the people who were on the bench. It wasn't long until it was 2-0.
Shola Shoretire broke through the middle to place Facundo Pistri, and the winger rounded Derby substitute goalkeeper David Marshall for the score.
Pellistri (19) spent the second half last season at Alaves in Spain on loan. He joined United from Penarol last summer for EUR10million.
Lingard was involved in the build-up to Pellistris goal. He almost scored another goal for Hannibal Mejbri, before smashing the crossbar with a powerful drive from the left corner of the penalty box. After beating Lee Grant 20 yards, Kazim-Richards won Derby's consolation.
Next, United will head to the UK for a week-long training camp before heading to London for Saturday's second preseason friendly against QPR.