Williams has been playing mainly on the ATP Challenger Tour since mid-2012 , as he was able to improve his world ranking position with good performances and a few wins on the ITF Future Tour . In August 2012 he was able to qualify for the US Open 2012 and even made it into the main draw of the tournament. In the first round he was clearly defeated by Andy Roddick in three sets. Other tournaments followed on the Challenger Tour, with a semi-finals being his best result. Williams received a wildcard for the Australian Open 2013 and met Florian Mayer in the first round , to whom he was defeated in just five sets. At the Challenger tournament in Dallas he reached a single final in this category for the first time and won it against his compatriot Robby Ginepri in two sets.