Cilic, seeded 11th and playing early, stopped Andrey Golubev 6-4, 6-2 without losing his serve while Nishikori, seeded 16th and in Monday's final match, defeated Paolo Lorenzi 6-2, 6-4 by saving all seven breaks he faced.
Philipp Kohlschreiber eliminated 14th-seeded Milos Raonic, the only other seeded player on the schedule Monday, 7-6 (7-2), 6-4. Kohlschreiber won nearly 80 percent of the points on serve and didn't allow Raonic a break opportunity.
Qualifiers Ernests Gulbis and Andrey Kuznetsov also gained second-round spots. Gulbis got by Jarkko Nieminen 6-2, 7-6 (8-6) while Kuznetsov moved on when Xavier Malisse retired with Kuznetsov ahead 6-2, 3-1.
Albert Ramos defeated Jan Hajek 7-5, 6-0 while Fabio Fognini ran past Andreas Seppi 6-4, 6-1 and Benoit Paire defeated Juan Monaco 7-6 (7-4), 1-6, 6-4. Also Monday, Jerzy Janowicz beat Santiago Giraldo 7-5, 6-2 and Potito Starace eliminated Radek Stepanek 6-4, 4-6, 6-3.