John Isner will take on Ivo Karlovic in Memphis, in a match between two of the tallest players on the ATP Tour.
Isner sealed his place in the Quarter Finals after he earned a hard fought 3 set victory over Jarko Niemenen of Finland, while Karlovic eased past Belgium's Xavier Malisse 6-4 6-4.
Isner who is 6ft 9 has been in good form this season, having won the 1st title of his career in Auckland he then reached the 4th round of the Australian Open before losing out to Andy Murray in straight sets.
Karlovic also reached the 3rd round in Melbourne but was beaten in 4 sets by Rafael Nadal.
Both men have had some superb results in Grand Slams, Karlovic beat Lleyton in the 1st round at Wimbledon in 2003 when the Australian was the defending champion while Isner beat America's number 1 Andy Roddick in the 3rd round at last year's US Open.