Hewitt joins Swiss world number one Roger Federer and hometown favourite Andy Roddick in the last four of the $4.45 million season finale, with Russia's Marat Safin taking on Britain's Tim Henman later in the evening to complete the field.
"Right at the moment I feel up for this event," said Hewitt. "I'm really motivated."
Masters champion in 2002 and 2001, Hewitt walked onto the centre court of the Westside Tennis Club aware he needed victory over the French Open champion in his last round-robin clash to reach the semi-finals for the third time in four years.
Knowing Gaudio has had the better of him this season in winning two of their three meetings, the Adelaide fighter left nothing to chance, brushing past the Argentine in 59 minutes.
All of Gaudio's successes over Hewitt had come on clay but on the Houston hard-courts the South American baseliner was no match for the fired-up Hewitt, who enjoyed a superb summer by collecting back-to-back titles in Washington and Long Island and a place in the U.S. Open final.
Hewitt had Gaudio under pressure throughout, breaking the Argentine to go up 3-1 and again to close out the opening set.
In the second a dejected Gaudio was easy prey for Hewitt, who stamped his authority on the contest with an early break and steaming to 4-1 lead.
Hewitt will meet Roddick in Saturday's semi-finals while defending champion Federer will face Safin or Henman.
"He's got a lot of firepower," said Hewitt of Roddick. "He has a massive serve and a huge forehand, you've got to try and make him play that extra ball.
"You've just got to take your chances against the best players in the world. You only get one or two."
