Isner suffers shock exit
John Isner was the biggest name to bow out of the Sydney International as a number of seeds failed to progress past the second round.
Top-seeded Isner slumped to a 6-4 6-4 loss to fellow American Ryan Harrison in just 71 minutes.
Isner, who was promoted to the No 1 seeding due to injuries to Jo-Wilfried Tsonga and Richard Gasquet, was joined by Fernando Verdasco and Florian Mayer in crashing out - with sixth-ranked Radek Stepanek pulling out injured.
Fourth-seeded Verdasco was blown away 6-3 6-3 by Denis Istomin, while Mayer, the No 5 seed, was beaten 7-6 (7-4) 6-2 by Bernard Tomic.
Julien Benneteau is through to the next stage after Stepanek pulled out with a back injury.
It wasn't all bad news for the seeds - with Andreas Seppi and Marcel Granollers progressing to the next round.
Seppi, ranked three in Sydney, beat John Millman 6-2 3-6 6-3, while No 8 seed Granollers saw off Fabio Fognini 6-2 7-6 (7-4).
Jarkko Nieminen also progressed with a 6-3 6-1 victory over Ivo Klec, while Kevin Anderson toppled Feliciano Lopez 6-3 6-4.