Lee Johnson described it as a "nearly performance" as Latics were beaten 1-0 at home by Ronnie Moore's Tranmere Rovers in Sky Bet League 1.
Latics' manager admitted it was a frustrating afternoon as they lost to an injury-time penalty from Ryan Lowe, a decision which incensed Johnson who was subsequently sent to the stand by referee Eddie Ilderton.
He said: "You could see what I thought about the penalty when I volleyed my jacket about four rows back.
"I have seen the incident again on the DVD and, all I can say, is that my reaction was justified."
Latics' manager added that James Tarkowski claimed he ought to have been awarded a penalty late in the opening half when an opponent climbed all over him.
Looking back over the game, Johnson added: "It was disappointing and a horrible one. There were some good bits to our play and bad bits.
"On another day we might have scored three, but we didn't. We nearly kept a clean sheet, but didn't and were done by two poor decisions.
"We played well in patches and, just when everybody was getting off their seats, the final ball wasn't quite right or the final contact.
"I think you saw we were the better side, yet Tranmere have come out and nicked a win they ought never to have got.
"I thought it was a very good performance in the first half without having that killer instinct.
"The second half was flat which was disappointing. I tried to mix it up by putting a new dynamic on which worked to a point.
"We were flashing balls in the box without anybody ever looking like getting on the end of them.
"We were never in doubt, never in danger and looked as though we were cruising. If we had upped our game five-per-cent, maybe we would have got two or three goals.”
Latics made two changes from the team which kicked off one week earlier against Port Vale as Connor Brown and Cristian Montano were replaced by debut-making Italian Matteo Lanzoni and Sidney Schmeltz who was handed his first start.
Right-back Brown was ruled out through a knee injury, but Lanzoni (pictured below) capped an impressive debut by being named Optima Cars Man of the Match.
Montano wasn't risked from the start as he had been suffering from a dead leg which enabled Schmeltz to make his full debut.
Latics made an impressive start creating three scoring chances in the opening six minutes.
Jonson Clarke-Harris headed wide, Schmeltz sliced a shot wide and Adam Rooney's glanced header flashed inches wide.
Korey Smith and Clarke-Harris both had goal-bound shots deflected off target as Latics maintained a stranglehold on the game.
Tarkowski then went close with a bullet header from eight yards following a corner by James Dayton.
A terrific cross from Tarkowski eluded Clarke-Harris and Dayton as it almost crept in at the far post.
Latics had a claim for a penalty rejected on the stroke of half time when Tarkowski was convinced he was fouled.
Tranmere had the first chance in the second period when a header from Jean-Louis Akpa Akpo looped just over the crossbar.
Latics made a double substitution in the 63rd minute in a bid to break the deadlock as Albert Rusnak was handed his debut and Anton Rodgers also brought on. They replaced Clarke-Harris and James Wesolowski.
And former Slovakia under-18 captain Rusnak almost made a dream start but his header from Schmeltz's cross was comfortably caught by keeper Owain Fon-Williams.
Johnson made his third and final change with 15 minutes left as Montano came on for Dayton.
Tranmere came close to snatching the lead in the 82nd minute when central defender Ash Taylor's header flashed just wide of the upright before Montano then had a shot turned over the Fon-Williams.
The game looked destined to end goalless when Tranmere were awarded a 93rd minute penalty when keeper Mark Oxley was adjudged to have brought down substitute Ryan Lowe.
Lowe picked himself up to score from the spot as Tranmere snatched victory at the death in the fourth and final minute of stoppage time.
Latics (4-4-2): Oxley; Lanzoni, Tarkowski, Grounds, Mills; Schmeltz, Wesolowski (Rodgers 63), Smith, Dayton (Montano 75); Clarke-Harris (Rusnak 63), Rooney. Subs (not used): Mellor, Millar, Philliskirk, Coleman.
Tranmere (4-3-1-2): Fon-Williams; Holmes, Taylor, Goodison, Horwood; Atkinson, Power, Koumas (Lowe 70); Rowe; Stockton, Akpa Akpo (Sodje 88). Subs (not used): Thompson, Kirby, Jones, Dugdale, Mooney.
The goal: Lowe (90+4 pen) for Tranmere.
Bookings: Lanzoni (81) for Latics. Rowe (65) for Tranmere.
Referee: Mr E Ilderton.
Attendance: 4,792 (586 visitors)