We enjoy a punt here at BackPageLead and have been known more than once to scream ”rigged” in jest as our well-backed favourite jogs in arse-first or misses a 15-metre shot for goal on the siren. Normally we’d put it down to the glorious unpredictability of sport. We might even make a mental note never to tip horse X or team Y again and move on.

That mental note has just been written for ATP players, Janko Tipsarevic, of Serbia, and Argentina’s Horacio Zeballos.

In the Kremlin Cup first round in Moscow on Thursday, the unfancied Zeballos defeated the favourite Tipsarevic 6-4, 4-6, 3-6. Nothing too strange about that, except the manner in which the match unfolded — and the illogical nature of the betting patterns through the contest — soon raised alarm bells and red flags.

Tipsarevic, the 26-year-old world No. 38, began the match favourite with most bookmakers at around $1.50. Zeballos, the 25-year-old world No.89, started as a $2.80 outsider.

Those odds were a fair reflection of their recent form. Zeballos had failed to win a match on the ATP Tour or in Davis Cup since August 2. Tipsarevic was hardly flying but had recently defeated highly ranked Czechs Thomas Berdych and Radek Stepanek to lead Serbia into the final of the Davis Cup. Moscow is also a favoured venue for the Serbian. He reached the final of the Kremlin Cup in 2009, the semis in 2007 and the quarters in 2006.

But then a strange thing happened. Despite such convincing arguments for Tipsarevic, Betfair, the world’s largest internet betting exchange, experienced a confusing pre-match drift on the Serb. In the lead up to the opening game, he slid out as far as $2.20, making Zeballos the favourite, which set betting forums alight with a mixture of conspiracy theories and outrage.

Did one punter or group of punters know something the rest of us didn’t?

Tipsarevic continued to drift as the match progressed and, despite winning the first set 6-4, he did not firm in the markets as you would expect — but drifted out to $2.80 at the beginning of the second set while his opponent shortened to about $1.55. The higher-ranked player, who had gone into the match with better form and was now one set ahead, was for some reason easing in the betting, while most of the money was for the Argentine. By now, even Blind Freddy could see that something wasn’t quite right.

Some of the world’s hardcore tennis punters, who exchange thoughts and observations on the Betfair tennis forum, began to give vent to their concerns.

Terry616 said: ”lol i backed (Tipsarevic) at like 2.4 before he even won the set. He wins the set and now its 2.8. uh oh.”

Vaprus Parnu said: ”Oh boy, this doesn’t look good ……”

Dstyle said: ”good god this is blatant.”

More than 700 comments were posted on that particular thread. To the surprise of few following the betting patterns, Zeballos claimed the final two sets to take out an otherwise unlikely victory.

Tipsarevic showed no signs of injury or illness during the match and afterwards offered no explanation other than to Tweet: “Biggest choke EVER…All my life playing like **** when I defend the points (finals here last year) on the same week…sigh…no comment…”

He seemed to get over it quickly enough, though, Tweeting three hours later, “Eating the best beef Stroganoff in the world. Pushkin restaurant in Moscow… :)”

Due to its global reach and ability to provide betting in-the-run on fixtures not normally carried by other bookmakers, Betfair is disproportionately exposed to contests out of reach of close scrutiny.

Betfair spokesman, Hugh Taggart, told BackPageLead that the agency was aware of the unexpected patterns in the Tipsarevic-Zeballos contest. He also confirmed that Betfair has settled all accounts on the market, which traded at around $3.5m — a figure considered high but not abnormal.

Betfair operates a Memorandum of Understanding with the ATP and if they consider the match to be of enough cause for concern they can choose to pass on their information to the sport’s governing body to progress any inquiry. To safeguard the integrity of the competition and the players involved, Betfair is unable to confirm if the ATP has been informed of any irregularities.

So it is now up to Betfair and the ATP to decide if the issue goes any further.

In the meantime, BackPageLead will think twice about outlaying any hard-earned on Tipsarevic or Zeballos matches any time soon.

*(Editor’s note: BackPageLead and Crikey is not implying or suggesting in any way that Betfair has acted improperly. We believe that any problem tennis might have with irregular results is up to the ATP and its anti-corruption unit to investigate.)

**Back Page Lead is a sports opinion website that provides sports content to Crikey.