Russia have taken a shot at its old enemy the United States by comparing Michael Phelps cupping therapy to banned substance meldonium.
Despite the 31-year-old American winning his 19th Olympic gold medal on Sunday, there was arguably just as much attention on the purple marks all over his body.
Immediately after Phelps won gold, fans were trying to work out if he'd been attacked by leeches or been on the receiving end of a brutal paintball firing squad.
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What is cupping therapy?
Cupping therapy is a suction-based massage in which heated glass cups are applied to the skin. Practitioners claim that cupping helps to cure muscle problems and it is very popular among members of the US olympic team.
Athletes have claimed that it eases aches and pains and helps with the physical recovery of constant training and competition. Though it is be legal under IOC rules, Russian state TV had its own thoughts on the potential benefits - which are still under question.
"Following the Hollywood trend, the method was adapted by athletes," said the Russian report, via a translation from Mashable. "According to them, vacuum-based massage improves circulation and overall well-being, suggesting that muscle repair happens faster after physical exertion.
"In other words, the net effect from such practices in many ways, is not unlike those of meldonium."
Meldonium rose to prominence earlier this year when Russian tennis star Maria Sharapova received a two-year ban from the sport after testing positive for the substance.
US swimmer Lily King heightened tensions on Sunday when she described her self "not a fan" of Russian rival Yuliya Efimova, who had previously served a drugs suspension.
Meanwhile, Phelps, the most decorated Olympian of all time, extended his Olympic gold medal tally to 21 yesterday with wins in the 200m butterfly and men's 4x200m freestyle relay.
Is Phelps the greatest Olympian of all time? Have YOUR say in the comments box below!