Match-fixing has been suspected in at least four matches played at New Zealand's premier tennis tournament over the past five years.

The Herald can reveal one match played at the Heineken Open in 2011, one in 2012 and two in 2014 have caught the eye of those investigating suspicious betting patterns on the ATP Tour.

One player who is understood to have been "red-flagged" to betting and tennis authorities was involved in two of the questionable matches.

Tournament director for the 2011 and 2012 editions, Richard Palmer, yesterday said that while he had no knowledge of anything untoward in the particular matches identified and can "barely recall" the player supposedly involved twice, players were often accused of tanking - the practice of losing on purpose - at the Auckland tournament.

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"Some players just wanted to get off to Australia," he said. "You knew certain guys were not really trying but know you can't help but wonder whether they were not trying because they'd played a match or two and wanted to get to Melbourne [to prepare for the year's first grand slam, the Australian Open], or were they not trying for other reasons."

While tanking is frowned upon by authorities, there is a big difference between losing so you can move on to the next tournament early and losing to order for betting syndicates.

The four matches in question at Auckland saw late spikes in money on a certain result.

In all four early-round contests, large pre-match bets came in on the player who was favoured with the bookmakers, shifting the odds for the match by well over 10 per cent.

The four players who were heavily bet on to win all did so, with two games being won in straight sets and the other pair taking three sets to complete.

In one particularly startling 2014 encounter, money flooded in on a first-round clash, with the underdog seeing his odds increase by over 50 per cent as bettors plumped for his opponent. That player- at the time ranked higher in the world rankings than his opponent - succumbed meekly in straight sets.

The Herald has chosen not to list the matches or players suspected of cheating.

None of the matches played have been definitively linked to match-fixing, but the players on the losing side of the encounter have come under scrutiny for regularly losing matches where suspicious betting patterns were discovered.

The Auckland news emerges as more details around the dark side of professional tennis emerge in the wake of the Buzzfeed/BBC investigation.

The four matches at the Heineken Open - now renamed the ASB Classic - each involved a player in the "Buzzfeed 15", the names of whom have been released on various blogs that have reverse engineered the algorithm used to identify suspicious betting patterns on the ATP Tour.

Some of the methodology used by Buzzfeed has been found to be flawed, but it nevertheless shines a light into the darkest recesses of professional sport.

Buzzfeed tracked major shifts in pre-match betting odds, analysing data from 26,000 professional matches from 2009 to 2015.

By selecting matches where the pre-match odds shifted by more than 10 per cent, they discovered 15 players who regularly lost matches in which large bets came in on their opponent. However, the study acknowledged that suspicious betting patterns aren't proof of fixing, with many variables at play when it comes to movement in betting odds.

Sometimes, news about a player's injury can alter the odds, or the movement can simply be a result of betting agencies setting incorrect odds for the match in question.

It is also possible that due to Auckland being so early in the season, there would be little information on the condition of the athletes in question, resulting in matches that would be difficult for bookmakers to price accurately.

These variables can lead to rapid market corrections - corrections that can be innocent, as tennis blogger Ian Dorward demonstrated by debunking many match-fixing suspicions over games two-times grand slam winner Lleyton Hewitt was involved in.

Despite their methodology lacking context, Buzzfeed argue that it is highly unlikely that the 15 players would repeatedly underperform in matches where they have irregularly large sums bet against them.

Match-fixing has long been suspected to be rife in tennis, but not necessarily at the upper echelons.

Palmer recalls being at tournament directors' meetings at Wimbledon and the US Open when seminars were held by the now under-fire integrity unit. The sums being legally bet on in tennis - the third-most popular sport for gambling - were staggering, Palmer said.

"The talk was mainly that this was happening at Challenger level, where there were few spectators and the players, many of whom knew they were never going to 'make it', were more susceptible to approaches."

In 2007, top-10 Russian player Nikolay Davydenko was investigated for match-fixing, and last year two Italians, Daniele Bracciali and Potito Starace, were banned for life by the Italian tennis federation as the result of an inquiry. Starace was later cleared of match-fixing, while Bracciali's ban was reduced to a one-year suspension.

Tennis officials are set to carry out an independent review into their anti-corruption practices as a result of the claims.

Chairman of the Association of Tennis Professionals Chris Kermode acknowledged the need for greater transparency from the Tennis Integrity Unit, which has been accused of not doing enough to investigate suspicious activity.

However, Kermode noted that although the suspicious betting patterns are a red flag, they are not proof of corruption in the sport.