BRISBANE, AUSTRALIA - Second-seeded Frenchman Gilles Simon and eighth-seeded Aussie favorite Bernard Tomic were among Monday's first-round winners at the 2012 season-opening Brisbane International tennis event.

The world No. 12 Simon subdued American Ryan Sweeting 6-3, 6-4, while the 19- year-old Tomic held off French veteran Julien Benneteau 6-2, 4-6, 7-5 on the hardcourts at Queensland Tennis Centre.

Simon's second-round opponent will be Aussie wild card James Duckworth.

A Day-2 upset came when Uzbekistan's Denis Istomin took out fourth-seeded German Florian Mayer 7-6 (7-5), 2-3, as Mayer retired from the bout.

In other first-round play, Luxembourg's Gilles Muller held off Brazilian Ricardo Mello 6-7 (3-7), 7-6 (7-4), 6-3 and former Australian Open runner-up Marcos Baghdatis of Cyprus bested promising American Ryan Harrison 7-6 (9-7), 6-4.

This year's top seed is last year's Australian Open runner-up Andy Murray, who will open his 2012 campaign against Kazakhstan's Mikhail Kukushkin on Tuesday.

The winner of this $434,250 Aussie Open tune-up will claim $74,370.