A late goal by Port Vale striker Uche Ikpeazu undid all the hard work for ten-man Latics after coming back from another two goal deficit.
Seven days on from one of the greatest comebacks in the club’s history, a repeat looked on the cards after goals from Chris McCann and a Sam Foley own goal drew Latics level with just four minutes on the clock.
But after Barnett was shown a red card for bringing down last man Enoch Andoh, Latics just fell short despite giving it everything to get back into what turned out to be a real thriller.
Caldwell made a couple of changes before the game. The injured Sean Murray was replaced by McCann in midfield while Max Power dropped to the bench to accommodate Jonjoe Kenny in defence after international duty with England U19s. Will Grigg only made it onto the bench after his time with Northern Ireland.
In a cagey opening half an hour, there was plenty of attacking intent but neither team were able to conjure up any real chances, the closest coming on 31 minutes, Haris Vuckic finding space to wriggle clear of his marker in the box, Craig Davies fired in a low cross but McCann just wasn’t able to apply the final touch in a crowded area.
But then came the opener on 34 minutes and it was a gift. Carl Dickinson crossed from the left, the ball reached McCann at the far post, who looked to have cleared the danger but his pass fell straight at the feet of Anthony Grant, who took a step towards goal and fired in from the edge of the box with a powerful finish.
Latics had a chance to equalise immediately afterwards when Davies shot low across the face of goal, Vale keeper Jak Alnwick spilled the ball, which eventually fell to David Perkins, who shot over.
Latics then made a surprise double substitution in the 40th minute, Jody Hiwula and Andy Kellett replacing Vuckic and Donervon Daniels, as Caldwell switched to a flat back four and swapped Michael Jacobs over to the right side.
It looked for a moment as if Caldwell would have to make a third substitution when Barnett needed attention after Sam Foley’s powerfully hit drive struck him in the face in the 48th minute but he returned to the field.
Vale piled on the pressure in those early minutes after the break and Latics needed the outstretched limbs of both Barnett and Jason Pearce to stop strikes on goal.
Vale doubled their lead after a corner in the 65th minute the ball falling to Louis Dodds in the area and he swivelled and smashed the ball home into the roof of the net from close range.
Latics immediately responded by replacing Reece James with Grigg and drew instant dividends. Davies drove down the right hand side to get behind the Vale defence, he pulled it back from the by-line and McCann, on the penalty spot, was on hand to rifle it into the back of the net.
Could another remarkable comeback be on the cards? Roared by a following of over 1,300 behind the goal they were kicking towards, Latics came forwards again, Davies sliding in but Alnwick was able to save at the second attempt. Davies then slid another great effort across the face of goal before McCann shot straight at Alnwick. Jacobs then sent Grigg clear who went down under a challenge from Richard Duffy but no penalty was given.
Latics inevitably had to leave gaps defensively and had to rely on the outstretched fingertips of Richard O’Donnell to beat away an effort from the edge of the box from Dodds, before Ben Purkiss fired over with an angled effort.
With ten minutes to go and the game was still swinging from end to end, but it was Latics who scored. Hiwula’s shot was deflected for a corner after he was set up by Grigg, Latics forced a second corner and from Jacobs’ delivery Barnett rose above the defence, only to narrowly miss the ball, which bounced in off the head of Port Vale midfielder Foley.
Then more drama as Vale broke away through the Enoch Andoh, Barnett’s long legs halted his progress twenty-five yards from goal and the referee brandished the red card as he’s been clear on goal.
Perhaps it was too much to hope for. Latics were not able to clear the ball from the resultant free-kick and it eventually fell to Ikpeazu who bundled it home, in the 90th minute.