Fulham defender hailed his side's dream start to the new Barclays Premier League season as the Cottagers' smash-and-grab raid on the Stadium of Light dealt Sunderland's summer revolution a blow.
Pajtim Kasami headed home a Damien Duff corner five minutes into the second half to snatch the points in a 1-0 win in what was the visitors' only clear chance of the match.
But despite their evident relief at securing an unlikely victory, both Hughes and Fulham boss Martin Jol insisted much improvement is necessary in order to sustain their early momentum.
Hughes' rock-solid central defensive partnership with captain Brede Hangeland was the main reason the visitors managed to soak up the waves of attacks by the home side.
Hughes said "It wasn't vintage from us and I wouldn't put it down as one of our best performances but in terms of being resolute and strong and showing lots of character it is up there.
"To come up here in the first game of the season and come away with the three points is a big achievement. It's a confidence-booster for us and we look forward to doing it again next week."
Fulham's celebrations were dampened by injuries to Kieran Richardson, who hobbled off after 19 minutes with a hamstring complaint, and new keeper Stekelenburg.
The Dutchman suffered a shoulder injury when saving from Altidore in the 75th minute and had to be replaced. Although tests did not show a dislocation, the injury is likely to keep Stekelenburg out for the rest of the month.