Another late fightback wasn't quite enough for the Chairboys who were made to pay for earlier defensive lapses in a 3-2 loss to Southend at Adams Park.
Craig Mackail-Smith and Adebayo breathed life into a late surge from the hosts who had found themselves 3-0 down after Theo Robinson, Tom Hopper and Simon Cox took advantage of being afforded too much space in front of goal.
However, time ran out on the Chairboys' hopes of a comeback, who now look for a happier October, kicking off at Fleetwood on Tuesday night.
It meant starting roles for Jason McCarthy and Scott Kashket on their 50th appearances for the club, as the game began in bright sunshine with both sides enjoying spells of pressure in the first period.
Ben Coker’s first-time effort for the visitors was saved comfortably by Ryan Allsop on five minutes before Southend keeper Mark Oxley was called into action, holding Bryn Morris’s volley from Adebayo Akinfenwa’s flick down.
Tom Hopper headed wide and Theo Robinson missed a sitter from close range as the Essex club got on top, and Robinson again threatened with a low shot which was well denied by the legs of Allsop.
Wanderers improved, with Matt Bloomfield volleying narrowly wide and Akinfenwa planted a header over the bar from Fred Onyedinma’s cross, before Bloomfield again darted into the box but saw the ball whipped off his toes as he was set to pull the trigger.
The opening goal came moments later at the other end, and Theo Robinson could hardly miss, meeting Hopper’s low cross with a bundled effort from a yard out.
Back came the hosts, seeing Bloomfield’s left-footed strike held by Oxley down to his right, but United sat on their lead until the interval, giving Gareth Ainsworth plenty to ponder as he looked for the right adjustments to get back in the game in the second half.
There was moments of note within 30 seconds of the restart, with United appealing for a penalty as Sido Jombati closed down Hopper with what they thought was an arm, before Fred Onyedinma was set free into the box but was denied by Oxley as the keeper dived out to block the effort.
But when Southend’s second goal came, it was all too simple. Ben Coker was allowed to drive into the box unchallenged and his pass towards the centre of the six-yard box was tapped home by Hopper with ease, heightening the size of the uphill struggle facing the Chairboys.
And it got worse. A routine ball down the right channel from Jason Demetriou found Simon Cox onside and in acres of space, and a striker of his experience was never going to squander the opportunity, carrying it forward and placing it with ease beyond Allsop.
Southend were well on top, and Wycombe needed changes. They came via the introductions of Paris Cowan-Hall, Craig Mackail-Smith and Randell Williams, taking the place of Matt Bloomfield, Scott Kashket and Fred Onyedinma.
But by this point, the Shrimpers looked comfortably home and dry, and made their first changes when Stephen McLaughlin and Michael Kightly replaced Simon Cox and Theo Robinson.
Timothee Dieng headed a deep free-kick over the bar and Sam Mantom drilled a chance wide after closing down Dominic Gape, while a well-hit Bryn Morris shot landed straight at Oxley, and Randell Williams tested the keeper’s handling with an effort from further out.
The home crowd had something to cheer with a goal-of-the-season contender from Craig Mackail-Smith, who lashed home an exquisite volley on 85 minutes from outside the box, and he also turned a deep cross dangerously along the face of goal only for it to be cleared by a man in orange.
Then came another ray of hope when a deep free-kick found Bryn Morris at the back post and his low cross was converted by Akinfenwa, making it 3-2 with the clock heading towards 90.
Akinfenwa side-footed a shot which was held by Oxley as the game entered four minutes of stoppage time, and Mackail-Smith blasted a volley over the bar in a bid to replicate his earlier strike.
But – just as in Tuesday’s cup defeat to Norwich – Wycombe had left themselves too much to do and couldn’t find the late equaliser, succumbing to a 3-2 defeat.