(Changes slug, adds later games, quotes)
By Tom Bartlett
MONTREAL Aug 5 (Reuters) - Germany's Florian Mayer sent Australian young gun Bernard Tomic tumbling out of the Rogers Cup in Montreal on Monday, while Janko Tipsarevic's miserable run of results continued with a first round exit.
Mayer, ranked 50th in the world, came from a set down to win 5-7 6-3 6-3 as the year's sixth Masters series event began under blue skies and warm conditions.
Tomic has endured an inconsistent few months since the ATP banned his father and coach John for allegedly assaulting his practice partner in May.
He made a promising start on Monday but Mayer capitalised on the Australian's rising unforced error count at the start of the second set, and used his unorthodox backhand slice to great effect.
The 29-year-old German, playing his first hard-court match since March, needed just one break of serve to draw level before repeating the feat in the decider as he closed out victory in an hour and 37 minutes.
"I missed my chances, I didn't focus early on in the second set and that's when he took over," Tomic said. "I dropped my concentration and he played very well."
Mayer will face top seed and defending champion Novak Djokovic in the second round.
Tipsarevic's hopes of rediscovering the form that took him to number eight in the world last year were shattered in the evening session when he was humbled by Uzbekistan's Denis Istomin 6-4 6-3.
The 16th seed regularly held a top 10 spot during 2011-12 but has struggled for consistency this year, reaching the quarter-finals in just three of his last 15 tournaments.
BIG GUYS, BIG TOURNAMENTS
Japan's ninth seed Kei Nishikori had to work much harder for his win and was given a stern test under the lights before breaking down Canadian qualifier Peter Polansky 4-6 6-4 6-2.
Local fans did not go home too disappointed, however, as wildcard Jesse Levine, a former American representative who now plays under Canada's flag, outclassed Belgian Xavier Malisse 6-4 7-6(4) to earn a second round tie against Rafa Nadal.
Earlier, Latvia's Ernests Gulbis advanced 7-6(4) 6-4 over Spanish left-hander Feliciano Lopez.
Gulbis has long been touted as a potential top 10 player and at times showed why, edging a tiebreaker against the former world number 15 before his big serve helped finish the job.
Gulbis is a possible third-round opponent for Wimbledon champion Andy Murray.
"I like to play against the big guys on the big courts in the big tournaments," a confident Gulbis said.
Croatia's Ivan Dodig, who stunned Nadal in the second round at this tournament two years ago, crushed Slovenian Grega Zemlja 6-1 6-1 to set up a meeting with in-form sixth seed Juan Martin Del Potro.
Pablo Andujar, who like Dodig only squeezed into the main draw following the withdrawals of Viktor Troicki and Marin Cilic, also made the most of his opportunity by recording a straight-sets win over Israeli qualifier Amir Weintraub.
Italian Andreas Seppi, Frenchman Benoit Paire and the second Australian in the main draw, qualifier Marinko Matosevic, were also among the day one winners.
Seppi finally ended the resistance of Czech Lukas Rozol in a third set tiebreak while Paire and Matosevic were comfortable winners over the German duo of Philipp Kohlscreiber and Benjamin Becker respectively. (Editing by Stephen Wood/Peter Rutherford)