Ukraine nordic skier Marina Lisogor and Latvian ice-hockey player Vitalijs Pavlovs are the latest athletes to fail a drugs test at the Winter Olympics in Sochi.
The 30-year-old Lisogor became the third competitor to test positive for a banned substance during the Games, in this case trimetazidine, after two athletes failed doping tests on Friday.
And now Pavlovs, 24, has tested positive for methylhexaneamine.
Italian bobsleigher William Frullani failed an 'A' test on 18 February and his 'B' sample is also understood to have come back positive for the banned substance dymetylpentalymine, although the International Olympic Commitee (IOC) is yet to confirm this.
But the Italian Olympic Committee has sent him home and his place in the four-man bobsleigh team has been taken by Samuele Romanini.
German biathlete Evi Sachenbacher-Stehle was banned from competing any further in Sochi and sent home after testing positive for the banned stimulant methylhexaneamine.
But the two-time Olympic cross-country champion, who has a total of five medals from previous winter Games, protested her innocence.
"I cannot explain how this positive doping test came about," Sachenbacher-Stehle said, confirming all her dietary supplements were tested in a laboratory.
"I am living through the worst nightmare that you can imagine.
"I can only assure everyone that I have never knowingly taken a banned substance and will do everything to clear this up so there are no questions."
Despite an isolated number of competitors having now failed drugs tests, IOC spokesman Mark Adams insisted it was evidence of greater vigilance on their part.
He said: "Of course it is always disappointing when we catch people. But what it shows, I think, is a determination to catch cheats.
"No one wants to see cheats here, it affects the credibility of the Games.
"As you know the president (IOC president Thomas Bach) said on many occasions we have a record number of tests here. Not just a record number of tests, more smarter testing, too.
"So we have something like 57 per-cent more pre-competition testing than in Vancouver and something like 14 or 15 per-cent more tests in total. But it's much more targeted."