's-Hertogenbosch, The Netherlands (Sports Network) - Top seed David Ferrer led the charge into the quarterfinals at the UNICEF Open, a final grass-court Wimbledon tuneup.

The 2008 Den Bosch titlist cruised past Argentine Leonardo Mayer 6-3, 6-1 in exactly one hour at Autotron Rosmalen. The world No. 6 Spaniard's round- of-eight opponent on Thursday will be Dutch wild card Igor Sijsling.

Ferrer is the only seed still standing this week.

Day-4 upsets came when Japan's Tatsuma Ito drove out third-seeded Austrian Jurgen Melzer 6-2, 6-2 and France's Benoit Paire knocked off eighth-seeded Pole Lukasz Kubot 6-3, 0-6, 6-4.

In other second-round action, Frenchman Edouard Roger-Vasselin defeated Italian Flavio Cipolla 6-2, 3-6, 6-1; German qualifier Philipp Petzschner got past retired Croatian wild card Mate Pavic; Luxembourg's Gilles Muller drilled Colombian Alejandro Falla 6-3, 6-0; Belgian Xavier Malisse bested Italian Paolo Lorenzi 7-6 (7-3), 6-2; and Sijsling topped Belgian Olivier Rochus, 7-5, 7-6 (7-4). Pavic retired against Petzschner during their warmup on Wednesday.

Thursday's other quarters will pit Ito against Paire, Petzschner versus Roger-Vasselin and Muller against Malisse.

The newest UNICEF champion will collect $85,000.