Thrust into the spotlight following Andre Agassi's withdrawal, Chilean Fernando Gonzalez made the most of his Masters Cup cameo role recording a scratchy three-set victory over Mariano Puerta, to end the Argentine French Open finalist's chances of securing a Masters Cup semi-final berth.

Gonzalez's 6-3 4-6 6-0 win in his first Gold Group match as a replacement at the season-ending championships in Shanghai means Russian Nikolay Davydenko, who earlier in the day beat Gaston Gaudio of Argentina, earns a place in the Shanghai semi-finals.

On holiday since a second round exit at the Paris Masters, two weeks ago, Gonzalez was drafted into the field following Agassi's pull-out due to an ankle injury on Monday.

The question many were asking during the first game was: does Gonzalez practise while on holiday? Having lost the opening point, Gonzalez won eight consecutive points with a combination of baseline brilliance and lightning net rushes to break Puerta then held for a 2-0 lead.

The first Chilean to appear at the year-end tournament since Marcelo Rios in 1998 maintained his advantage throughout the first set.

Unable to guess the pace and direction of each of Gonzalez's serves at times Puerta lost his temper losing the opener 6-3 in 46 minutes.

The Argentine, under investigation for a positive dope test at Roland Garros this year, almost snapped Gonzalez again in the fifth game, but one break proved enough to seal a 36-minute second set.

Realising his future in the Masters Cup was in doubt 27-year-old Puerta reacted with a service break in the first game of the second set courtesy of two Gonzalez errors.

Puerta audibly swore at the umpire in Spanish after disagreeing with a line call that left him 2-0 down in the third set.

Gonzalez, a titlist on three different surfaces in 2005 including the recent Basel Indoors, rocketed through the final set with breaks in the second, fourth and final game for a bagel in 21 minutes.

The 25-year-old Chilean will now play Gaston Gaudio of Argentina in the final round robin match at the Qi Zhong stadium on Friday for a place in the last four.

"Five days ago I was on holiday and having fun. Two days I didn't think I'm playing," said Gonzalez. "Now I have a chance to be in the semi-finals. It's strange. Who knows?"