After clawing their way out of the bottom three last week, Wigan are back in trouble following a 3-2 home defeat by Sunderland. Martinez blamed the setback on the knee injury Ivan Ramis suffered at Fulham last week, which led to a defensive frailty, with Steven Fletcher moving onto 10 goals for the season with an impressive first-half double.
But Martinez is adamant that, after eight years in the top flight, no one at Wigan is resting on their laurels.
"We never take anything for granted," he said. "If we had done that we would never have had eight seasons at this level. We weren't good enough defensively for 30 minutes. We need to rectify that."
Wigan were staring down the barrel of a big defeat, but the half-time introduction of Roger Espinoza triggered an improvement and fellow new-boy Angelo Henriquez made his mark when he scored his first goal for Wigan 11 minutes from time.