MK Dons 2 (Alli 57, Grigg 64)
The Reds slipped to a two-goal defeat at promotion-chasing MK Dons but will feel harshly done by having been on top when conceding the first goal.
MK Dons' opener was the killer blow that deflated Danny Wilson's side and the hosts never really looked back as Ross Turnbull kept the score down to just the two.
The Reds made two changes to the side that slipped to a disappointing defeat at Doncaster last week with Ben Pearson and George Williams coming into the side. Mason Holgate started the first of a three-match ban on the sideline along with Dale Jennings making way.
With only four minutes gone, Will Grigg drew Lewin Nyatanga out of position before playing in Bowditch for a one-on-one with Turnbull. The striker tucked his effort under the Barnsley 'keeper but George Williams was on hand to clear off the line.
The Reds registered a shot on target with ten minutes played after Milan Lalkovic beat the offside trap down the left. The winger went for goal at Martin's near post but the 'keeper made a fairly comfortable save with Waring heading the rebound over the bar.
On 14 minutes the Reds made another break for it on the counter attack through Milan Lalkovic. His cross from the right this time was almost met by the head of Kiwomya but the Chelsea loanee just couldn't quite connect.
The Reds had grown into the game and had a great chance to find the net after Lalkovic once more beat the offside trap. After venturing into the area he hesitated on delivering a cross for Waring for what would have been a tap in which gave the hosts a chance to clear on 26 minutes.
Just before the half-hour mark, Williams missed a clearance at right back as Alli's ball found Powell in the area but he could only shoot straight at Turnbull.
On 34 minutes the home side had a goal ruled out for offside after some incredible play from Alli. The 18-year-old made a fool of Berry before crashing a shot off the post which then hit Turnbull before falling for Grigg but his finish was ruled out for offside.
Just before the break, Conor Hourihane had a chance to cause danger with a free-kick and he did just that. His delivery was met well by George Waring but he just couldn't quite steer an effort on target from eight yards out.
The Reds started the second half with confidence in abundance and finally took the game to the hosts in the opening stages of the second period.
Lalkovic sent in a dangerous cross that Lewington had to clear from under his 'keeper's nose with Waring lurking on 50 minutes.
With Barnsley finally looking confident and even in control, MK Dons took the lead on 57 minutes. Jean-Yves M'voto's headed clearance dropped at the feet of Dele Alli and he poked home from the edge of the area.
Will Grigg doubled his side's lead after completely evading the marking by Jean-Yves M'voto to meet Spence's delivery. He did well to take the ball down and past Turnbull for the easiest finish of his career on 64 minutes.
The Reds made a change on 70 minutes with Alex Kiwomya being replaced by Rhys Oates.
Ross Turnbull made a brilliant save a minute after Barnsley's first sub - Carl Baker turned Smith twice before thundering at goal which Turnbull had to block with a strong hand. The defence came to his rescue as the former Coventry City man's effort on the rebound was blocked.
Josh Scowen came on for his Barnsley debut as he replaced Luke Berry on 79 minutes and a third change came on 82 minutes - Phenix replacing Lalkovic.
Devante Cole was denied a goal on his debut as Williams once again made a brilliant save inside the six-yard box with a last-ditch tackle.
MK Dons: Martin, Spence, McFadzean, Kay, Lewington (c), Potter, Alli, Baker (Green 75), Bowditch (Clarke-Harris 65), Powell (Cole 65), Grigg.
Subs: McLoughlin, Hodson, Baldock, Carruthers.
Reds: Turnbull, Berry (Scowen 79), Nyatanga, Hourihane (c), M'voto, Smith, Williams, Pearson, Lalkovic (Phenix 82), Waring, Kiwomya (Oates 70).
Subs: Davies, Ramage, Digby, Lita.
Referee: Christopher Kavanagh