The Dons came from behind to beat Swindon Town 2-1 at stadiummk and leapfrog their opponents into third place.
Kay and Daniel Powell replaced Tom Flanagan and Samir Carruthers in the starting XI for the visit of the Robins.
In-form frontman Benik Afobe forced Wes Foderingham into a fine fingertip save from a dangerous Dean Bowditch free-kick as early as the first minute.
But it was the visitors who took the lead just five minutes later, Michael Smith crossing for Obika to tap from close range after a quick break.
The Dons responded well with Afobe seeing a teasing delivery palmed away by Foderingham with Alli lurking, before the former headed over from 10 yards on 12 minutes.
Once again Afobe was proving the home side’s biggest threat and he cleverly found space in the Robins box on 19 minutes to pick out Bowditch, who fired over the top from 20 yards.
At the other end, David Martin was out quickly to superbly smother Smith’s effort after the former Charlton Athletic was put through on goal by strike partner Obika midway through the first half.
Daniel Powell was increasingly growing into game and, after driving at the visitors’ defence, his low 20-yard drive tested Foderingham at his near post.
Powell and his team-mates continued to pose Swindon problems as the game ticked into the final 10 minutes of the first half, with Nathan Thompson clearing Ben Reeves’ goal-bound header from Bowditch’s corner.
The men from MK1 were limiting Swindon to rare forays forward, with Obika heading harmlessly over the top, whilst still looking threatening at the other end – Afobe directing a header not too far past the left-hand post from Reeves’ right-wing cross in the final real action of a Dons-dominated first period.
Robinson’s side continued on the frontfoot at the start of the second half with Powell seeing a shot saved prior to Reeves having a goal-bound effort well blocked by Jordan Turnbull.
Their pressure finally told in the 50th minute though, Alli expertly curling the ball into the top corner from 20 yards to level matters – his seventh goal of the season.
The returning Kay then fired the Dons in front from close range on 59 minutes after fellow centre-back Kyle McFadzean had flicked on Reeves’ free-kick into the danger area.
Afobe almost made it 3-1 shortly afterwards but, after robbing Thompson off possession and bearing down on goal, he pushed his effort just past the left-hand post.
However, Swindon were inches away from making it 2-2 when Harry Toffolo headed over at the back post when well placed.
There was a real ebb and flow about the game as it entered the final 10 minutes with the Dons trying to kill off Swindon, who themselves were trying to find an equaliser.
The Dons twice came close to a third in quick succession – firstly Will Grigg couldn’t quite connect with fellow substitute Carruthers’ cross before Powell shot straight at Foderingham from 15 yards in the 90th minute.
Swindon somehow survived a flurry of opportunities midway through the six minutes of injury-time – Darren Potter, Alli and Grigg all being denied when it looked a certainty for the Dons to wrap up the win, but it didn’t matter in the end as the men from MK1 extended their unbeaten run in the league to five matches in some style.
Starting XI: Martin; Spence, Kay, McFadzean, Lewington (c); Potter, Alli; Powell, Reeves (Carruthers 70), Bowditch (Baker 80); Afobe (Grigg 86).
Unused subs: McLoughlin, Hickford, Flanagan, Randall.
Goals: Alli (50), Kay (59).
Bookings: McFadzean, Potter, Bowditch, Kay, Lewington.
Attendance: 9,494 (1,292 Swindon fans).