It was Marijanovic who got off to the better start after he recovered from missing set darts in leg three to take a 1-0 lead in sets.
The second set also went to a decider, with both players missing the bull and North missing two further darts at double four. The German stepped in to double his lead to 2-0.
Another deciding leg saw 'Northy' peg a set back with a dramatic last-dart 64-checkout. Marijanovic took a 2-0 lead in set four, but finishes of 136, 84 and 56 under pressure from North sent the match into a deciding set.
Set five was the only set not to feature a decider as it saw the Englishman force a crucial break of throw in leg three, before hitting tops to triumph and set up a match with Steve West in round two.
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World Darts Championship, including schedules and the prize fund breakdown.
William Hill World Darts Championship
Saturday December 15
Afternoon Session (1230)
Richard North (92.82) 3-2 (85.99)
Robert Marijanovic (R1)
Mickey Mansell v Jim Long (R1)
Josh Payne v Jeff Smith (R1)
Max Hopp v Danny Noppert (R2)
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