World number five Nishikori needed two hours 45 minutes to see off wild card Berlocq, the 34-year-old world number 77 to set-up a Sunday title showdown against Ukraine's Aleksandr Dolgopolov who beat Spanish fourth seed Pablo Carreno-Busta 7-5, 6-2.
Nishikori made the final on hard court in Brisbane in January but was beaten by Bulgaria's Grigor Dimitrov in three sets.