Clint Dempsey's hat-trick helped Fulham avoid a potential upset in their FA Cup third-round tie with Charlton.

The US international's goals helped the Cottagers triumph in a London derby in which the League One leaders' performance belied the scoreline.

Fulham benefited from a strong lineup at Craven Cottage as their manager, Martin Jol, stuck by his word not to name a weakened side, with Kerim Frei the only change to the side that defeated Arsenal on Monday.

His counterpart, Chris Powell, kept largely the same side that defeated Brentford earlier this week, with John Sullivan and Matthew Taylor drafted in.

Fulham were under pressure during the opening exchanges but soon benefited from their attack-minded philosophy. Moussa Dembélé forced Sullivan into a superb one-handed save in the sixth minute and the Cottagers took the lead two minutes later, when Dempsey latched on to a deflected through-ball from the former Charlton midfielder Danny Murphy.

Boosted by up to 7,000 visiting fans, Charlton attacked with intent and only fine goalkeeping from David Stockdale prevented them netting an equaliser. First Yann Kermorgant hit a neat curled chip that forced Stockdale to parry wide, although Johnnie Jackson could only fire the rebound into the side-netting.

Then Stockdale made a superb reaction save to deny Bradley Wright-Phillips from close range, before tipping over Danny Green's follow-up from outside the box.

Dempsey netted again on the hour mark, playing a one-two with the Costa Rica international Bryan Ruiz before directing the ball past Sullivan.

The 28-year-old secured progression to the fourth round with nine minutes remaining, converting from the penalty spot after Ruiz was brought down by the onrushing Sullivan.

The substitute Damien Duff scored a late deflected effort to round off the scoring.