The news that Pakistan fast bowlers Shoaib Akhtar and Mohammad Asif have tested positive for the banned steroid nandrolone has rocked the cricket world.
Shoaib could face a two-year ban if his positive test is confirmed
The pair are the most high-profile players to test positive since Shane Warne was banned from cricket for a year in 2003 for testing positive for two separate diuretics.
But why might a player risk taking nandrolone - and how likely is it that they could be the innocent victim of a easily-made mistake?
WHY A CRICKETER MIGHT TAKE IT
Some within cricket question whether any player would deliberately take performance-enhancing drugs, pointing to the diverse range of complex skills needed to compete at the top level.
The results of tests carried out in Britain each year by UK Sport certainly don't appear to indicate that the sport has a big problem.
In the last three years, only three players have tested positive for banned substances, and all three were for recreational drugs - Keith Piper being banned for cannabis use, Asim Butt for ecstasy and Graham Wagg cocaine.
But - in theory at least - a cricketer might find plenty of reasons to take nandrolone, as Britain's leading expert Professor Ron Maughan explains.
Reduces fatigue and recovery time after training
Increases strength and power by promoting muscle growth
Can increase aggression
"Nandrolone is an anabolic steroid, which means it builds and repairs muscles, so it can help make people bigger and stronger, and it can lead to increased aggression," Maughan told BBC Sport.
"There are lots of potential benefits for a fast bowler - not least increased speed while playing and quicker rebuilding of muscle while recovering from injury."
In other words, while taking nandrolone could not magically enable a bowler to reverse-swing a ball or pitch it on the perfect length, it could allow them to practice and play for longer, to bowl faster and to bowl more aggressively.
It could also speed the recovery of a player from injury.
Both Shoaib and Asif have recently returned to action after spending most of the summer injured.
And ICC chief executive Malcolm Speed said on Monday: "Generally cricket has been considered a low-risk sport. But the risk for cricket has always been a player who is injured taking a substance inadvisably to come back quickly from injury."
HOW IT COULD BE TAKEN ACCIDENTALLY
Nandrolone stands apart from many other banned doping products for one key reason: it can easily be taken unwittingly.
As Maughan's own ground-breaking research proved six years ago, some legal dietary supplements and protein powders can contain traces of the drug.
Maughan says: "Many of the dietary supplements on the market contain traces of nandrolone or related compounds that will cause a positive test.
If you produce a positive test, then technically you are guilty
"We also know that there are still some supplements companies which are less than honest - some of these contaminated supplements are labelled as having been tested by government laboratories when they haven't been.
"When it states that on the label, you have to sympathise with the athlete who believes what they read.
"There may also be a culture within the team of taking vitamin supplements or mineral or protein powders as part of a general well-being policy.
"Yet sometimes even some of those apparently harmless supplements can contain prohibited substances."
In theory, both Shoaib and Asif could claim that they unwittingly took nandrolone in a supplement they thought was clean, or one that was given to them by team officials.
But, if the Pakistan Cricket Board stick to ICC rules, neither of those arguments would make a difference.
Greg Rusedski was a rare example of a sportsmen cleared after testing positive for nandrolone
Under ICC regulations - taken from the World Anti-Doping Agency's code - the offence is having a positive urine sample, not in knowingly taking a drug.
As Maughan says, "If you produce a positive test, then technically you are guilty."
It is extremely hard to prove that the nandrolone in your system came from contaminated supplements.
"You might think that, if they were taking supplements, they could just bring in the supplement for testing to prove that they took it accidentally," says Maughan.
"But of course the athlete might have taken the last tablet in that bottle - there might be none left to be tested. We know too that in some cases some tablets in the bottle contain nandrolone and others don't."
The testing procedure itself also cannot tell the difference between nandrolone that has been deliberately taken in large quantities and that ingested in tiny amounts from a supplement.
"If you inject it into the muscle, you can produce very low levels for many months afterwards," says Maughan.
"If you take nandrolone orally in very large doses, you'll be clear in a couple of days. If you take it in a very small amount, like the amount you might find in a dietary supplement and take by accident, you can be positive for just one urine sample and then be clear again.
"The values are very hard to interpret. You don't know if someone took a large dose a couple of days ago or took a trace amount accidentally a few hours ago. Therein lies the difficulty for the testers."
At this stage, neither Shoaib nor Asif have officially failed a drugs test. Until their B samples are tested and confirm the A sample's reading, they are technically in the clear.
There have been high-profile cases recently when an athlete's A sample has come up positive, only for the B sample to prove negative - not least when Marion Jones' B sample failed to find the traces of EPO that her A sample had shown.
But nandrolone is not like EPO, which has been shown capable of providing a false positive under certain conditions.
"I don't think there has ever been a B sample in a nandrolone case that doesn't confirm the A sample," says Maughan.
"We have to presume it will be likely to happen."
The players' best hope in this case is that the PCB show them leniency.
While the PCB's Saleem Altaf has indicated that they are likely to follow the ICC's regulations, the PCB does not actually have an official doping code.
That may allow the board to let the pair off with less than the ICC's mandatory two-year ban.