David Ferrer survives as seeds tumble in Auckland

Defending champion David Ferrer survived a scare to reach the quarter-finals of the Auckland Open on Wednesday, as four seeded players exited early in a day of upsets.

The Spanish world number three, top seed this year at the tournament he has won four times, recovered from a sluggish start to down American qualifier Donald Young 6-7 (5/7), 6-3, 6-1.

"It was difficult, I started off very bad making a lot of mistakes," Ferrer said.

"In the second set I tried to play more focussed, be myself and it worked. In the third one, I could play my tennis."

German second seed Tommy Haas could not conjure a similar escape, beaten 6-4, 6-4 by big-hitting American wildcard Jack Sock.

Haas's compatriot Daniel Brands, seeded ninth, lost 7-5, 4-6, 6-3 to another American Bradley Klahn, while California native Steve Johnson was responsible for ousting two high-profile names from the tournament.

Johnson overcame Cypriot Marcos Baghdatis 7-5, 6-7 (3/7), 6-4 in a first-round match rescheduled from Tuesday due to rain, then a few hours later beat South African fourth seed Kevin Anderson 7-5, 6-4.

French sixth seed Benoit Paire lost 6-3, 6-4 to Roberto Bautista Agut of Spain.

Both third seed John Isner of the United States and German fifth seed Philipp Kohlschreiber emerged from their second round encounters unscathed.

However the pair will meet in the quarter finals on Thursday, further opening the draw as Ferrer chases a record-breaking fifth Auckland title.