This was the 12th league game this season in which Barnsley had the majority of the ball possession (55%) and not won the game.
Barnsley conceded more than once in a game for the 16th time in 26 Championship games.
Derby have now won each of their past five home league matches against Barnsley, a run stretching back to the 2012-13 season, prior to this the Reds were unbeaten in four at Pride Park (W1 D3)
The Reds have though now lost 11 of their last 15 trips to Derby and have won only one of the last 16 - a 3-2 victory in September 2009.
Derby won their opening match of a calendar year for the first time since 2015 whilst Barnsley lost their first since 2013.
Excluding play-offs, Yorkshire teams have won just two of their last 32 away league visits to Derby - both wins for Leeds in August 2015 and August 2018.
Barnsley conceded a league goal on half time for the first time since October 2018 against Luton.
Gerhard Struber brought off Mike Bahre for Elliott Simoes after just 26 minutes, the earliest Reds change since Kenny Dougall went off with a broken leg after 18 minutes at Doncaster in March 2019.
It is the second time Bahre has been taken off in the first half this season (also after 31 minutes against QPR)
Simoes then went on to grab his first senior goal (on only his third ever appearance), thus becoming the third substitute to net for the Reds this season after Patrick Schmidt (2) and Conor Chaplin.
Martyn Waghorn put the Rams back in front, he has scored against the Reds in two of the last three seasons after also netting against them for Ipswich in 2017-2018.
Barnsley have failed to win any of their last 46 league games in which they have been behind at half time (D9 L39) (if lose to Derby) last winning when behind at the break at Crewe Alexandra in February 2016.
There were no Barnsley bookings for the first time in seven outings.
1. Samuel Radlinger
2. Jordan Williams
5. Bambo Diaby
6. Mads Andersen
10. Mike-Steven Bähre
16. Luke Thomas
19. Patrick Schmidt
22. Clark Oduor
24. Aapo Halme
27. Alex Mowatt (c)
28. Elliot Simoes (for Bahre 26)
7. Jacob Brown (for Schmidt 52)
4. Kenneth Dougall, 20. Callum Styles, 21. Toby Sibbick, 32. Dylan Mottley-Henry, 40. Bradley Collins
12. Ben Hamer
2. Andre Wisdom
9. Martyn Waghorn
14. Jack Marriott
16. Matthew Clarke
23. Duane Holmes
25. Max Lowe
32. Wayne Rooney (c)
33. Curtis Davies
38. Jason Knight
41. Max Bird
46. Scott Malone (for Waghorn 74)
49. Morgan Whittaker (for Marriott 82)
3. Craig Forsyth, 19. Chris Martin, 21. Kelle Roos, 37. Jayden Bogle, 40. Louie Sibley.
Derby manager Philip Cocu said:
“I am extremely happy with the win because it is a very good result for us and we’ve now got back-to-back wins.
“We did it and the way we did it in the last game, with ten men against Charlton, and we put in a lot of effort and you could see it today.
“We knew it would be difficult but we played a great game, especially at the start. We had to score a one or two goals and then it would have been, possibly, an easier game.
“In many occasions this season we have really had to fight for our win; the players did it again.”
Sky Bet Championship results:
WEDNESDAY 1ST JANUARY 2020
Millwall (7th) 3-1 Luton Town (24th)
Birmingham City (18th) 2-3 Wigan Athletic (22nd)
Bristol City (11th) 0-4 Brentford (3rd)
Fulham (5th) 1-2 Reading (14th)
Huddersfield Town (20th) 2-5 Stoke City (21st)
Batth og 50
Nottingham Forest (4th) 3-2 Blackburn Rovers (13th)
Grabban pen 25
Worrall og 71
Preston North End (10th) 0-2 Middlesbrough (16th)
Davies og 62
Queens Park Rangers (15th) 6-1 Cardiff City (12th)
Sheffield Wednesday (8th) 0-1 Hull City (9th)
West Bromwich Albion (2nd) 1-1 Leeds United (1st)
Ajayi og 52
THURSDAY 2ND JANUARY 2020
Derby County (17th) 2-1 BARNSLEY (23rd)
Swansea City (6th) 1-0 Charlton Athletic (19th)
Barnsley lie in 23rd place in the Sky Bet Championship with 21 points from 26 games. We are 20 points outside the Play-Offs, 31 points outside the Automatic Promotion Places, 31 points outside First Place and 3 points inside the Relegation Zone.
Up to 2/1/20
On The Road:
FA Cup Third Round: Crewe Alexandra v Barnsley, Sunday 5th January 2020. Kick-Off: 2:01pm
Sky Bet Championship Matchday Twenty Seven: Barnsley v Huddersfield Town, Saturday 11th January 2020. Kick-Off: 3pm