Jamie Murray and John Peers missed five match points in a heartbreaking loss to defending champions Bob and Mike Bryan.
It was a straight shoot-out for a place in the semi-finals and Murray and Peers looked poised for victory at 9-5 in the first-to-ten deciding match tie-break.
Three chances slipped away but victory was in their grasp on the fourth as Peers pulled his racquet back for what appeared an easy putaway only to blast a forehand long.
And it was two more errors from the Australian that ultimately proved decisive as the American twins clinched a 7-6 (7/5), 6-7 (5/7), 16-14 win to move through to the last four.
It was a horrible end to a hugely fruitful three-year partnership for Murray and Peers, who have both found new partners for next season. At least for Murray there is the Davis Cup final to look forward to against Belgium next weekend, where he will hope for a more uplifting conclusion.
Earlier, Italians Simone Bolelli and Fabio Fognini finished Group Ashe/Smith with a 1-2 record.
The fifth seeds completed their campaign with a 6-1, 1-6, 10-5 victory in 61 minutes over eighth seeds Rohan Bopanna and Florin Mergea, who were already assured of topping the round-robin group.
Fognini and Bolelli, having lost their first two group matches, broke into a 5-1 lead in the Match tie-break and went on to record their 26th match win of the season, which included winning the Australian Open by beating Pierre-Hugues Herbert and Nicolas Mahut.
Bopanna and Mergea will now prepare for tomorrow’s semi-final against the Group Fleming/McEnroe runners up.