Canada's Daniel Nestor and Max Mirnyi of Belarus will play for the ATP World Tour Finals title in their first year as doubles partners.
Nestor and Mirnyi dispatched top-seeded American brothers Bob and Mike Bryan 7-6 (6), 6-4 in Saturday's semi-final.
"It's a long season and it's not easy to play at your best for the entire time," Nestor said. "I'm really pleased with our effort."
The 39-year-old Nestor, from Toronto, served out the winner in 78 minutes with the team's 13th ace, a scorcher down the middle.
"We played great and served really well," said Nestor. "We kept the pressure on them when they made some shots."
A victory Sunday will give Nestor and Mirnyi their fourth trophy in their debut 2011 season after winning the French Open, Memphis and Shanghai. They were beaten by the Bryans a month ago in the Vienna final and are 3-4 in 2011 finals.
"We feel good, we're playing our best tennis of the year in the autumn, perfect timing," Nestor said. "We're excited to be in the final against either one of a pair of tough teams. It's going to be a challenge no matter whom we play."
They will play the winner of the semifinal between Poland's Mariusz Fyrstenberg and Marcin Matkowski and India's Mahesh Bhuptahi and Leander Paes.
Nestor is gunning for his fourth title at the season wrap-up event, after winning it in 2007 with Mark Knowles of the Bahamas, and in 2008 and 2010 with Serbia's Nenad Zimonjic.
Overall the Canadian is 31-19 in his 13 year-end showings.
Nestor and Mirnyi never faced a break point and broke the Americans once, beginning the second set with a break.
The Bryans lost their second match in 24 hours after going down in a group contest at the round-robin season wrapup.
Nestor is seeking his 75th career doubles title, tying him for sixth in the all-time Open era list.