Andre Agassi put in a typically determined performance to beat Argentinian David Nalbandian to a place in the Masters Cup semi-finals in Houston.
The American struggled to keep Nalbandian at bay - saving five set points in the first set, including three in a 22-point tie break - on his way to winning 7-6 (22/10) 3-6 6-4 after breaking his rival in the final game of the match.
The victory means Agassi, 33, is the oldest man to reach the semi-finals of the year-end championships since the 35-year-old Arthur Ashe made the last four in 1978.
Earlier in the day Rainer Schuettler qualified for the semi-finals when he defeated Andy Roddick 4-6 7-6 (7/4) 7-6(7/3).
Roddick, who received the ATP Champions Race Trophy after the match for clinching the year-end number one ranking, plays Guillermo Coria, with the winner to claim the final semi-final spot.
Argentina's Coria joined Roddick in having won one out of two when thrashing Carlos Moya of Spain 6-2 6-3.Reuse content