SHENZHEN, China, Oct 30, 2012 (AFP) - The four-time Major-winner said he was tormented for a fortnight after the United States threw away a commanding position against Europe in front of their home fans in Chicago.
"I think the first two weeks following the Ryder Cup was a really tough low, one of the biggest lows of my career," he said in China before this week's WGC-HSBC Champions, his first event since the Medinah defeat.
"It was a very emotional time because we really thought we were going to win. We expected to win: we were playing well, we thought that we were going to win it on Sunday.
"It was one of the biggest disappointments that I've had to deal with throughout my career."
Mickelson, the world number 19, has experienced many highs and lows in his 20 years on tour, and he said the American team would be wrestling with their disappointment until the next Ryder Cup at Gleneagles in 2014.
The American team were 10-6 going into the final day, but were blown away 14 1/2 to 13 1/2 in the singles by their determined European rivals in one of golf's most memorable comebacks.
"I think that the disappointment will last a lot longer than a month. I still feel disappointed from it," said Mickelson, who won the WGC-HSBC Champions in 2007 and 2009.
"I feel that over the next two years, we'll still have the same disappointment from not winning this year's Ryder Cup."
Keegan Bradley, who enjoyed a successful partnership with Mickelson at Medinah, said he was unable to read or watch coverage of the event after Europe's barn-storming comeback.
"It was really difficult, because you have such mixed emotions," said the 2011 PGA Championship winner. "For me it was just such an amazing week, and then to see that we lost was tough.
"I didn't watch any Golf Channel or read anything, because it was too difficult."
Mickelson and Bradley are among 16 players from this year's Ryder Cup taking part in the star-studded WGC-HSBC Champions at Mission Hills in Shenzhen from Thursday.
Ten of the European team are playing, including WGC-HSBC Champions defending champion Martin Kaymer, who holed the winning putt at Medinah, along with Ian Poulter, Lee Westwood and Luke Donald.