Now, the hottest team on the ATP are pointing their sights on qualifying for the eight-team season finals in London next November.
Pospisil has now established the year-end World Tour Finals as the benchmark for a breakthrough season, with Pospisil and Sock provisionally standing ninth.
"It was a great week for us. We have to continue with the solid results if we want to make the finals," Pospisil said. "This was a great step towards that. Hopefully we can keep working and make it."
Pospisil, from Vancouver, and Sock had won 14 consecutive matches since getting together on the eve of Wimbledon and starting their collaboration with the Grand Slam title at the All England Club, where they beat the Bryans in the final.
They followed up last month by winning in Atlanta in their second-ever outing.
The partners set a record in modern tennis, surpassing the previous best start by a new doubles team of 12-0 set in 1984-85 by Paul Annacone and Cristo Van Rensburg.
"We had a great run but you just can't feel incredible in every match," said Pospisil. "We've played a lot of good matches this summer.
"Today we struggled with timing. But the Bryans were playing great and they jumped on us. Our first serves let us down a bit, but that's normal considering how well we've ben doing for."
The Bryans, ranked No. 1 in the world, dumped Pospisil and Sock team in just 53 minutes, breaking three times and saving the only break point they faced.
Pospisil and Sock are now headed for the US Open where they will try to duplicate their rookie Grand Slam success.
"It was obviously fun to play those guys again," said Mike Bryan. "Wimbledon was such a great match going down to the wire 7-5 in the fifth.
"We weren't look at it as a revenge thing. Just another shot to win a title here in Cincinnati against a great team, against a really hot team. That's the first match they've lost, so it's a very impressive run by them."