World number one Roger Federer returned to his vintage best as he thrashed Andy Roddick to qualify top of his group for the Masters Cup semi-finals on Friday.
The defending champion has lost three times in recent weeks but he roared back to form with some exhibition tennis, dismissing the fifth-ranked American 6-4, 6-2 in just 61 minutes.
The Swiss triple champion sets up a last-four showdown with arch-rival Rafael Nadal on Saturday, while Roddick will play David Ferrer.
"I was impressed with my own performance, actually," Federer said.
"If I'm on top of my game, indoors I'm favourite (against Nadal) but it depends on form on the day."
Federer had already been assured of a semi-final spot thanks to Nikolay Davydenko's 6-4, 6-3 win over Fernando Gonzalez.
"Let's not overrate today's match," he said. "We had both qualified and we could both play freely."
Federer indeed struck with nonchalant ease in the third game, defeating Roddick with a delicate stop-volley and a triple parry at the net before the American double-faulted to go a break down.
Looking relaxed and in control, Federer duly went a set up in 33 minutes as he punched another volley past the American.
Roddick, pounding his foot with his racquet in frustration, was two breaks down in the second before holding serve, and was never in the running as Federer took the first match point with a stylish forehand.
Federer has not lost to Roddick since 2003, a run of 11 matches including three Grand Slam finals.
"It seems like most times we play he's on top of his game, which is a little annoying," said the dejected American.
"I have to find out what about my game brings out the best in him and try to adjust."
Federer, the 2003, 2004 and 2006 champion, had earlier reached his sixth successive Masters Cup semi-final courtesy of Davydenko's win over Gonzalez.
The Swiss went through on a superior sets record to Gonzalez despite being shocked by the Chilean in his opening round-robin match. Davydenko had already been eliminated.
Davydenko, playing only for pride, edged a tense, 66-minute first set when Gonzalez put a forehand into the net, giving the Russian his second break in eight chances.
Gonzalez, needing a win to stay in the tournament, smashed up his racquet in anger and the outburst seemed to do the Chilean good as he broke in game one of the second set.
However Gonzalez faded after being broken back immediately and Davydenko finally converted his fourth break point in the eighth game before nailing an overhead on his first match point to seal it 6-3.
"I lost my first two matches but winning the last gives me confidence. Now I can go on holiday!" said Davydenko.
"My confidence wasn't so great but I won a few points coming to the net and volleying and I finished strongly."
Davydenko had only given up one set in his previous meetings with Gonzalez, winning all three matches comfortably.
The Russian, who reached the Masters Cup semi-finals in 2005, had already been eliminated after defeats to Roddick and Federer. He will now have a short break before this month's Davis Cup final against the United States.
The 26-year-old is coming off a difficult year after the ATP launched an investigation into suspicious betting patterns surrounding a match he played in August.
He was also fined for not trying after committing a series of errors in a shock defeat to Croatian qualifier Marin Cilic in St Petersburg, although the penalty was later rescinded on appeal.
Federer's defeat to Gonzalez in Shanghai, came after consecutive losses to Argentina's David Nalbandian, completing his worst run since 2003.