Toronto's Daniel Nestor and Serbian partner Nenad Zimonjic were beaten by American Eric Butorac and Raven Klaasen of South Africa 6-2, 6-4 on Thursday in the semifinal of the Australian Open.
The defeat leaves the 41-year-old Nestor to concentrate on the mixed-doubles event after winning 12 straight matches and winning Australian titles in Brisbane and Sydney with two different partners.
"This was a little bit of a let down, but all credit to them," said Nestor. "They came out firing an showed why they were in the semifinals. They were going for their shots and making them.
"They played really well, very aggressive. We started slow and that probably gave them confidence."
The match lasted just 64 minutes, with Zimonjic losing serve twice in the opening sat. Nestor, holder of a record 83 career doubles titles, was unable to carry the entire load as he and Zimonjic re-united this season after a few seasons with other partners.
Nestor's team lost to an unseeded team which has knocked out Australian Patrick Rafter and Lleyton Hewitt plus the world No. 1 Bryan brothers from the United States.
"We didn't assert ourselves and that's what the top teams should do," said Nestor. "On paper we were the best team remaining in the semifinals.
"This was a chance lost to possibly win a Grand Slam — and who knows when we might get that chance again."
Nestor won his only Australian men's trophy in 1998 with Mark Knowles of the Bahamas, the first of his four finals at the event.
Nestor and Zimonjic finished with 19 winners but never earned a break point and were broken three times.
Montreal's Eugenie Bouchard was preparing to play for a place in the women's singles final as the Canadian teenager faces fourth seed Li Na in the semifinal.