(MENAFN - Kora) The Japanese star should enter the ATP 250 event in Memphis as a hot favourite being the only top-20 player in the draw.
Last year's runner-up Feliciano Lopez is the second seed, with Australian Lleyton Hewitt the only other man in the top 50 at the event.
It shapes as being Nishikori's tournament to lose, although he was beaten by Hewitt at the Brisbane International earlier this year.
The top seed's form since has been impressive as he made the Australian Open fourth round and won both of his Davis Cup singles rubbers against Canada.
Hewitt is in Nishikori's half, with sixth seed Sam Querrey and Michal Przysiezny (seventh) the next highest.
There appear to be few other threats to the two in the top half, unless there is drastic improvement from Cypriot wildcard Marcos Baghdatis.
Baghdatis the 2006 Australian Open runner-up has failed to win in three attempts this year and has slipped well outside the top 100.
German Bjorn Phau enjoyed a good week in Zagreb, reaching the semi-finals, but whether he can back that up remains to be seen.
Lopez has been given a handy draw despite a potential second-round meeting with big-serving Croatian Ivo Karlovic.
Karlovic has won his past two meetings against the left-handed Spaniard, but the last of those was in 2008.
Australian fifth seed Marinko Matosevic faces a tricky first-round encounter against Czech Jiri Vesely in the same quarter.
Kazakh Mikhail Kukushkin and Chinese Taipei's Yen-Hsun Lu are the other seeds and have three qualifiers in their quarter.
But only an inspired run or a below-par Nishikori look capable of denying the defending champion a second straight title.