The Scot - ranked number 37th in the world - lost the first frame in Bendigo when he clipped in a long red only for the white to unfortunately drop via the black.
With the aid of a free ball, Selby cleared with 30 to move 1-0 ahead, but it would be a brief moment of satisfaction in a match that slowly ran away from the Leicester player.
Burnett enjoyed the better moments of the next two frames with a 69 in the third frame carrying him 2-1 clear.
That became 3-1 when he escaped from a tough safety shot to fluke the yellow before mopping up the necessary colours to sneak the frame having opened with a 46.
Selby produced 83 in the fourth frame only for Burnett to respond with a 61 to move within one frame of the last 16.
Buoyed by a long game working to some effect, Burnett was narrowly deprived of eking out a tactical seventh frame by Selby's patient approach - the former Masters champion reeled in 27 foul points with a timely snooker - late in the frame.
Burnett overcame Selby in their only other meeting, and would emulate his success with a supreme break of 62 in the eighth frame that included a few more eye-catching recovery pots. He will face Marco Fu in the second round.
There was no such joy for Burnett's compatriot Alan McManus, who was given short shrift by Ding Junhui in suffering a 5-0 loss
McManus's ambitions of causing a stir in his first match in the last 32 of a tournament for several years evaporated after he opened with a 62 break only to lose the first frame.
Ding's voracious appetite for piling on the points held sway as McManus suffered for failing to bring his own scoring game to the party.
The key to McManus's future health in the contest appeared to rest on his decision to refuse a tough green down a side cushion into the green pocket using a rest in the opening frame.
Ding had contributed 53 for a 62-0 lead only for McManus to run in 62 with five colours left up. Potting green with the rest and holding for the brown appeared problematic prompting the former world number six - who can be found at 56 in the rankings these days - to refuse the pot.
A safety error seconds later handed Ding the chance to slot brown, blue and pink to conclude the frame before the double UK champion ran way with the match in one hour and 20 minutes.
McManus was first among the balls on a couple of occasions, but his misses were accentuated as Ding provided 68, 113 and a 76 to secure a meeting with Peter Ebdon in the last 16.
Barry Hawkins eased himself into a match with Matthew Stevens courtesy of runs of 55, 57, 40 and 42 in completing a 5-1 win over Xiao Guodong.
Martin Gould progressed with a 5-3 win over Ken Doherty. He will meet China's Cao Yupeng.
In the opening second round matches, the 2005 world champion Shaun Murphy lost the first frame to a break of 50 against Tom Ford before winning the next five for a 5-1 win. Ford was a willing victim with his game blighted by misses.
Murphy's best breaks were 40, 80 and 95. He will face Ding or Ebdon in the quarter-finals on Friday.
Stephen Lee rolled in 71,126 and 51 in ousting Jamie Cope, who won his two frames in a 5-2 loss with knocks of 99 and 49.
Lee awaits the winner of the match between Fu and Burnett.
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