There may still be 10 weeks until Christmas, but MK Dons were in the giving mood as they gifted Portsmouth's Oliver Hawkins two first half goals to take the spoils at Fratton Park.
Costly errors from Ethan Ebanks-Landell after 14 minutes, and then Scott Golbourne on the stroke of half time left Hawkins with simple tap-ins to inflict back-to-back defeats league defeats on Robbie Neilson's side for the second time this season.
In a game of few chances and little quality, the mistakes were the only difference between the sides, though the home side had the better of the scant opportunities in the second period.
After missing the last game on international duty, Callum Brittain and Ouss Cisse returned to the Dons line-up for the trip to Fratton Park. Scott Golbourne also missed the last two through injury and returned at left back, while Aidan Nesbitt came in as the fourth change to Robbie Neilson's side. George Williams, Dean Lewington and Kieran Agard dropped to the bench, while Aaron Tshibola suspended after his red card last week.
Tshibola was guilty of gifting possession away before he clipped the heels of Bradford's Jake Reeves to earn his early bath, and it was a similar mistake, this time from Ethan Ebanks-Landell, which handed Portsmouth the lead on 14 minutes. Under hitting his pass to Brittain, Ebanks-Landell's ball was intercepted by Matty Kennedy, who raced into the area before squaring for Oliver Hawkins to rattle the home side ahead.
For much of the opening half, Dons were left chasing. Portsmouth played at a rapid tempo but it wasn't helped by Dons' poor passing, particularly from out of defence. While neither winger could make an impact, Sow was left to fight for himself up front, making for a quiet afternoon for Pompey keeper Luke McGee.
Dons' defensive woes continued when Callum Brittain hobbled off shortly before the interval, but it was the other full back, Scott Golbourne, who would be at fault as Portsmouth doubled their lead on the stroke of half time. Failing to clear as he dallied on the ball in the area, Jamal Lowe picked the defender's pocket to square for Hawkins again to beat Nicholls - two simpler finishes he couldn't ask for.
A formation and personnel switch at half time brought about a much more lively MK Dons in the second half. Nesbitt, who's fancy footwork never got going, was replaced by Chuks Aneke as the visitors switched to playing three at the back.
Despite Dons looking a more dangerous outfit, the home side should have wrapped it up on the hour mark when Kyle Bennett was first to Lowe's deflected ball in, but somehow poked wide when scoring looked easier.
The game never really developed from the scrappy affair it began as, with the football by and large poor for both sides, and neither keeper especially troubled.
Dons remain 14th in the table despite the defeat.
Referee: Graham Horwood
Attendance: 17,608 (580)
Portsmouth: McGee, Clarke, Burgess, O'Keefe, Hawkins, Kennedy (Evans 81), Donohue, Lowe, Thompson, Bennett, Close
Subs not used: Bass, Rose, Naismith, Talbot, Oxlade-Chamberlain, Haunstrup
MK Dons: Nicholls, Brittain (Williams 42), Wooton, Ebanks-Landell, Golbourne, Cisse, Gilbey, Upson, Nesbitt (Aneke 46), Ariyibi, Sow
Subs not used: Sietsma, Lewington, Walsh, Agard, Seager