Roger Federer doesn't suffer too many losses, but he remembers  them all.

Russian qualifier Evgeny Donskoy denied three match points in the second-set tie break and reeled off six consecutive points in the decider completing a shocking 3-6, 7-6 (7), 7-6 (5) upset of Federer in Dubai in February.

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It was the Australian Open champion's his first loss of the season, the biggest upset in Dubai history and marked the first time Federer lost to a player ranked outside the Top 100 on hard court since he fell to James Sekulov at the 2000 Indianapolis.

So when Donskoy recently ran into Federer in the bathroom before his US Open clash with compatriot Mikhail Youzhny, Donskoy's mentor and practice partner, the Wimbledon champion offered a facetious greeting.

"I even saw Federer before their match," Donskoy told the St. Petersburg Open website. "I was washing my hands and then he saw me, said 'Hi' and asked if I was coming to watch their match.

"Oh, yes', I told him.

"He replied with a smile: 'Oh, no…'

"But that was a joke."

Photo credit: Dubai Duty Free Tennis Championships Facebook