Gael Monfils of France was the only seeded player to progress in a day of upsets in the second round of the Stockholm Open on Thursday.
Top-seeded Monfils took three sets to beat Bernard Tomic of Australia 6-4, 6-7 (4), 6-4. Monfils now faces the fifth-seeded South African Kevin Anderson in the quarterfinals.
Unseeded Argentine David Nalbandian took the most emphatic victory of the day. He beat seventh-seeded Ivan Dodig of Croatia 6-1, 6-1 and now goes through to play James Blake, who beat second-seeded Juan Martin Del Potro on Wednesday.
Jarkko Nieminen of Finland upset third-seeded Stanislas Wawrinka of Switzerland 6-3, 6-4 in the second round, while fourth-seeded Juan Ignacio Chela also exited.
Nieminen set himself up for a quarterfinal against Tobias Kamke of Germany, who won his second-round match against countryman Sebastian Rieschick 6-3, 6-1.
Grigor Dimitrov of Bulgaria beat Chela 6-2, 5-7, 6-1 and will play the sixth-seeded Milos Raonic in the quarterfinals.