World number four Ivan Ljubicic and US Open runner-up Andy Roddick secured their places in the season-ending Masters Cup on Tuesday.

The duo are third and fourth in the ATP Race and join the world's top two players, Roger Federer and Rafael Nadal, in the eight-man field for the November 12-19 tournament in Shanghai.

Ljubicic will be making his second consecutive appearance at the event. The 27-year-old Croat has a 60-18 win-loss record this year and has won titles in Chennai, Zagreb and Vienna.

Roddick was a semi-finalist in 2003 and 2004, when the Cup was in Houston - but skipped last year's event through injury.  He is on course to finish in the top five for a fourth consecutive year, vaulting up the Race standings with an 18-2 record during the North American summer circuit after enlisting the services of former world number one Jimmy Connors.

Ljubicic's qualification was confirmed when Spaniard Tommy Robredo, eighth in the Race, lost his first-round match at the St. Petersburg Open.

Roddick booked his place after Cypriot Marcos Baghdatis, 10th in the Race, fell to Frenchman Arnaud Clement in Lyon. With less than two weeks left of the regular season, Robredo and Baghdatis are two of the 10 players vying for one of the remaining four berths in the Shanghai draw.