World number one Roger Federer battled past Croatia's Ivan Ljubicic 6-3, 2-6, 7-6 on Tuesday to close in on the semi-finals at the season-ending Masters Cup.

The Swiss, who has just recovered from a six-week injury layoff, bounced back from a poor second set to make it two wins out of two at the troubled $4.45 million event in Shanghai.

Federer squandered three match points at 5-3 and 5-4 in the third before sealing 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 achieved three-in-a-row.

Federer was assured of finishing the second round of matches on top of the Red Group with Argentines Guillermo Coria and David Nalbandian, who lost their openers, playing later on Tuesday.

The Masters Cup was hit by the sudden pullouts by former world number one Andre Agassi and French Open champion Rafael Nadal through injury on Monday.

The withdrawals were a further blow to organisers after the pre-tournament pullouts of Andy Roddick, Marat Safin and Lleyton Hewitt.