Goals from second-year scholar Kyran Wiltshire and Daniel Powell cancelled out David Cassidy’s opener as Karl Robinson’s men came from behind to beat the Irish Premier Division side.
The Dons started at a good tempo and Danny Green almost picked out Kabongo Tshimanga but there was just a little too much on his through-ball.
However, it was Bray who nearly took the lead in the 13th minute when David Scully headed wide when well-placed at the back post.
Lee Hodson was then across quickly to deny the Wanderers’ powerful striker Ismahil Akinade before Gary Curran couldn’t find a team-mate after getting to the byline.
At the other end, Darren Potter forced Stephen McGuinness into a smart save with a clever header from a Green corner prior to Wiltshire firing over from 25 yards midway through the half.
Just as the men from MK1 were growing into the game, they were caught on the counter-attack on 27 minutes by David Cassidy, who turned smartly inside before delicately lobbing David Martin.
Robinson’s men had more of a spring in their step at the start of the second half, and the hosts had substitute keeper Shane Redmond to thank for keeping them ahead on 55 minutes, pulling off a fine stop to deny Summerfield’s close-range header finding the back of the net.
Trialist Jay McEveley had a strong penalty appeal waved away shortly afterwards when he seemed to have his left leg taken from under him as he prepared to shoot.
The Dons’ pressure finally told on the hour mark when second-year scholar Kyran Wiltshire fired home from close range after McEveley’s initial shot had been saved by Redmond.
This was followed by an array of changes as David Martin, Hodson, Antony Kay, McEveley, Gedeon Okito, George Baldock, Summerfield, Green, Wiltshire and Tshimanga were replaced by Charlie Burns, Lewington, Kyle McFadzean, Harry Hickford, Dele Alli, Ben Tilney, Daniel Powell, Giorgio Rasulo, Dean Bowditch and Tom Hitchcock.
Bray also made a host of substitutions and one of them, Gareth McDonaugh, hit the crossbar with a powerful effort while, at the other end, a Powell shot deflected comfortably into the arms of Redmond.
Rasulo then rasped an effort off the top after robbing a defender of possession, but neither he nor a team-mate could get on the end of Powell’s dangerous cross on 79 minutes.
The Dons saw another strong penalty shout turned down when Powell appeared to be tripped in the Bray box before Burns pulled off a brilliant stop, tipping Sean Hurley’s drive on to the post a minute later.
Hitchcock had the ball in the net in the 88th minute but his effort was ruled out for offside. That didn’t deter the Dons though who won the game a minute later when the impressive Powell raced on to a through-ball, rounded Redmond and coolly slotted the ball home.
MK Dons: Martin (Burns 60); Hodson (Lewington 60), Okito (Tilney 62), Kay (McFadzean 60), McEveley (Hickford 60); Potter (Randall 55), Baldock (Alli 60); Green (Powell 60), Wiltshire (Rasulo 60), Summerfield (Bowditch 60); Tshimanga (Hitchcock 60).