"I thought it would be a long match," Roger said after his terrific display. "His level dropped considerately towards the end, but you have to get him to that point first. I'm happy not to have wasted any further energy after the five sets against Berdych."
Del Potro is regarded as one of the rising stars of men's tennis, having stormed up the rankings from No.65 midway through last year. But he had a nightmare match on Tuesday night, cast in the role of mouse to Roger's cat, as our former world No.1 toyed with his opponent before producing a swift kill.
Roger playfully pulled off an audacious array of shots from all parts of the court just two days after being forced to come back from two sets down against Tomas Berdych.
The first set was effectively over by the fourth game, when our three-time champion broke 20-year-old Del Potro for a 3-1 lead and served out. By the second set, the match was a procession. Roger reeled off 13 games in a row - taking the set 6-0 and picking up three consecutive breaks in the third as a visibly deflated Del Potro struggled to maintain interest in a match that, in his head, he had already lost. And so it proved as a clinical Roger showed no mercy, serving two aces in the final game as he finished off his demoralised opponent in emphatic style.
Roger is looking forward to meeting Andy Roddick in the semifinal. He does, after all, boast a 15-2 head-to-head record over the American seventh seed. He will have particularly fond memories of his last Australian Open meeting with Roddick, when he gave up just six games in winning their semi-final two years ago. However, their last competitive meeting saw the American emerge victorious at the Miami Masters last year.