Roberto Martinez admitted that Fulham had shown their experience after seeing his Wigan side go down 2-1 at home in the Premier League.
Wigan old boy Hugo Rodallega headed Fulham in front and Damien Duff added a second after the interval to leave the Latics with a mountain to climb.
Arouna Kone gave Wigan hope with a late goal but there was not enough time to find an equaliser, and Martinez acknowledged after the final whistle that Fulham had performed well in an open game.
"Today we played against a Fulham side who showed their experience. They are really well organised and for us it was a little bit too open," he told Sky Sports.
"There were too many chances and the difference was that Fulham took their chances at the right time.
"We had really good opportunities that we could not convert."
Wigan have now lost two games in a row and Martinez has called for calm from his players as they strive to rediscover the sort of form they showed at the start of the season.
He explained: "The start of the season has been very good in the level that we have shown, and then we have an international break and all of a sudden we get anxious to get positive results and we should be a little bit more cool about that."