Roger Federer has escaped a major upset by Croatia's Ivan Ljubicic at the season-ending Masters Cup, prevailing 6-3 2-6 7-6 to become the first man to reach the semi-finals.

His place in the last four was sealed when David Nalbandian beat fellow Argentine Guillermo Coria 7-5 6-4 in the second match.

World number one Federer, who has just recovered from a six-week injury layoff, made it two wins out of two in the Red Group at the troubled $US4.45 million ($A6.12 million) event in Shanghai.

He squandered three match points at 5-3 and 5-4 in the third before clinching victory 7-4 on a tiebreak to stay on course for a third straight Masters Cup title.

Only Ilie Nastase in 1971-73 and Ivan Lendl in 1985-87 have won three in a row.

"I arrived here this week basically on one leg," said Federer, who blasted three aces in the tiebreak to crush Ljubicic's resistance.

"I thought I was the worst injured of all. For me to play well is fantastic because this is like a grand slam."

Federer, who also beat Nalbandian in three sets at the weekend, extended his winning streak to 33 matches and his mark for the year to 79-3.

The Swiss played with his right ankle heavily taped and called the trainer for a quick rubdown at the start of the third set, prompting groans from the Chinese fans.

"I felt like my leg was starting to tighten up," said Federer.

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