Canadian Daniel Nestor and partner Max Mirnyi of Belarus lost 6-2, 6-3 in the Monte Carlo Masters doubles final to Americans Bob and Mike Bryan on Sunday.
The 39-year-old from Toronto was looking to win the event for the third time in the past four years, after lifting the trophy with former partner Nenad Zimonjic in 2009 and 2010.
"I played like I was 40," joked Nestor, who leads the all-time list with 77 career doubles titles. "They beat us pretty well today. They really deserved it.
"We have a long history with these guys. They got us today but was will have another chance soon."
The match lasted only 57 minutes as Nestor's side committed four double-faults and failed to convert on all three of their break points.
The Bryans lifted the first set in 24 minutes with breaks of both Mirnyi and Nestor, who double-faulted on a set point.
The American duo caught Nestor's serve in the fourth game for a 3-1 lead and were never troubled.
Mirnyi managed a love game for 2-4 and Nestor put a winning return through Bob's legs in the next game.
Match point had to be replayed after the chair umpire ruled that a Bryan had headed a volley as it missed his racket. Nestor netted on the second attempt to end the contest.
The result leave the Bryans atop the ATP rankings. The position would have changed hands had Nestor and Mirnyi won, with only 90 points separating the teams and 1000 at stake for the week.
"They've kicked our butts all over the world so it was good to win this one," said Mike Bryan.
Nestor and Mirnyi began this season with a title in Brisbane and a month later added Memphis.
Nestor last held No. 1 in 2010 after Wimbledon. The team was facing the long-time rival Bryans for the first time this season.
"I'm only sorry this wasn't the best doubles final ever," said Nestor.