London:Mahesh Bhupathi and Mark Knowles' doubles' partnership ended on a disappointing note after the third seeded Indo-Bahamian pair was handed a straight-set defeat by Americans Bob and Mike Bryan in the semifinals of the ATP World Tour Finals here.
The Bryan brothers, who are two-time former winners here, won 6-4, 6-4 on Saturday at the O2 arena in south-east London.
This was Bhupathi and Knowles' final match as partners.
In a hugely successful second season together, the Indo-Bahamian duo reached two Grand Slam finals, finishing runners-up at the Australian Open and US Open.
Next season will see Bhupathi team up with Max Mirnyi, while Knowles will combine with Mardy Fish.
In the match yesterday, the Bryan brothers were pushed to the backfoot early on by a fast start from the vastly experienced third seeds, who broke the Americans' serve in the opening game with an exquisite backhand volley by Bhupathi.
Strong returns from the Bryans gave them chances to break back in the fourth game, though, and they were able to level as Knowles double-faulted.
The Bryans later clinched the first set in the 10th game as a forehand from Bob clipped the top of the net and landed just inside the baseline.
In a closely fought second set, neither team was able to make a breakthrough until the 10th game, when some fine net play by Mike, who exhibited stunning reflexes, earned them three match points.
The Bryans were able to capitalise on their second break point after another telling return forced the error from their opponents after 64 minutes.
If the American twins avenge their round-robin defeat to Max Mirnyi and Andy Ram in the final, they will claim the year-end number one in the ATP Doubles Team Ranking for the fifth time after finishing as champions in 2003 and from 2005-07.
"It's going to be so loud tomorrow, it's going to be a big final, packed house," said Mike Bryan.
"No better place to play than out here. It's going to make for a huge occasion. It's going to be a special feeling walking out there, competing at our hardest," he added.
The 31-year-old Bryan twins are bidding for their third title at the year-end championships, having won back-to-back trophies in 2003 and 20004 when it was staged in Houston.
The Bryans will contest their 12th tour-level final of the season and are bidding for their seventh title.
They captured their seventh Grand Slam crown at Australian Open at the start of the year and went on to win a further five titles, triumphing most recently at the China Open in Beijing.