Martinez is not downhearted by Wigan's recent results and was able to take positives from a Latics performance that he feels was hampered by Gomez's dismissal.
He said: "I am not concerned with three defeats in a row. The way we played in the first half I was really pleased with ourselves. The sending off changed it for us but now we need to move onto the next game.
"Playing with 10 men away from home is going to affect us and then they scored a goal it was a real mountain, but I thought we defended really well.
"The referee's decision [for Gomez's sending off] is disappointing when he does not treat the two teams the same way."
Wigan currently sit 16th in the Premier League table, with four points from their opening six matches.