The Latics were never tested during the 4-1 triumph.
Martinez said: "I was very pleased with our overall display because I'll never under-estimate scoring four goals away from home against this Huddersfield side, who I've watched a lot in recent weeks and must admit I've been very impressed.
"We were respecting Huddersfield a lot and I was pleased we played really well as a team.
"We coped with their threat really well, we moved the ball well, kept it well on a difficult pitch and overall did not look like a team who had made six changes and that's the work, that's what we're looking for within the club to develop youngsters that can step into the side and know what they're doing.
"Our desire in the FA Cup is as strong as it is in the league. We've been in the Premier League for eight seasons and there will be no bigger achievement if we make it nine and we're also in the quarter-finals of the FA Cup."