However the more experienced Melzer settled into the match, getting back to 4-4 before sending the first set into a tie-break where he raced to a 4-0 lead of his own.
The vocal centre court crowd got right behind Guccione who rallied back, but a sensational passing shot by Melzer brought about set point on his serve which he won clinically to secure the set 7-6.
Guccione once again broke Melzer early in the second set, but when serving with the chance to go to 3-1 the Victorian-born player double faulted to bring the score back to 2-2.
The unforced error opened the door for the Austrian and he never looked back, eventually winning the set 6-3 to book a place in the quarter-finals against the Czech Republic's Tomas Berdych.
Vaidisova Czechs in to semis
Earlier, Czech Republic's Nicole Vaidisova, the youngest player at the tournament, defeated Serbia's Ana Ivanovic 6-4, 6-2, to advance to the semi-finals in the women’s draw.
17 year-old Vaidisova, who was kitted out in a shiny yellow and white outfit, slid through to the semis with a convincing win in just over an hour on centre court.
A vocal section of Serbian fans in the crowd got right behind 19 year-old Ivanovic, but it didn't help her situation on court as she served seven double-faults to stumble out of the tournament at the quarter-final stage.
Ranked 11 in the world, Vaidisova will now meet another Serb, Jelena Jankovic, in the semi-finals, by which time she will be well accustomed to dealing with the raucous Serbian supporters.
Jankovic, ranked 12, caused a big upset earlier in the day when she thrashed defending Australian Open champion and world number three Amelie Mauresmo 7-5, 6-0, also in just over an hour.
21 year-old Jankovic had a first serve winning percentage of 90% as she continues a superb run of form after being victorious at the ASB Classic tournament in Auckland earlier in the month.
Clijsters powers on
In other day four matches, Belgian Kim Clijsters defeated Israel's Shahar Peer 6-2, 6-1, to book a place in the women's semi-finals against China's Na Li who beat Slovenian Katarina Srebotnik 7-5, 6-1.
Cypriot star Marcos Baghdatis progressed to the men's quarter-finals with a tough 6-4, 6-7, 6-3, win over the Czech Republic's Jan Hernych, while James Blake defeated Australian Nathan Healy 6-2, 6-4, to also advance to the quarters.
Blake will play Russia's Evgeny Korolev while Baghdatis will take on Carlos Moya from Spain on centre court on Thursday.