Roberto Martinez felt the red card shown to Jordi Gomez was harsh as he watched his Wigan side slide to a slender 1-0 defeat at Sunderland.
Gomez was sent off just two minutes into the second half for a dangerous lunge at defender Danny Rose and a game in which his side had enjoyed the better of the opening 45 minutes turned on its head.
And the Spaniard was left aggrieved with Howard Webb's decision as he believed it changed the course of the match at the Stadium of Light.
"It did change the course of the game because straight after, we conceded a goal," Martinez told Sky Sports.
"Rose has controlled the ball in a 50-50 situation and Jordi is showing his studs, but it was with one leg and there was the same challenge with (Seb) Larsson on (Arouna) Kone in the 90th minute. You want the same decision for both teams.
"The match needs to be his call, but obviously it also needs to be a level playing ground for both teams which is the biggest disappointment.
"But we are more disappointed with the three chances we couldn't convert in the first half because we started the game really, really well and we had three outstanding opportunities, but then the red card unfortunately affected us too much and leaving the Stadium of Light with nothing is hard to take."