Cross-country skier Johannes Dürr of Austria has tested positive for the blood booster EPO and has been suspended from the Olympic team. Meanwhile, Russia has taken an unassailable lead in the medals table.
The Austria Olympic Committee (ÖEC) said on Sunday that Dürr had been caught in an out-of competition test on February 16. The B-sample has not yet been examined, it said.
It said he had tested positive for the performance-enhancing drug EPO, or erythropoietin, which improves the oxygen supply to muscles. EPO became particularly notorious for its use amongst cyclists.
"We are shocked about the news and have taken the necessary action," ÖEC president Karl Stoss said in a statement.
Stoss said the athlete has been dropped from the Austrian team and sent home. Dürr had been considered a serious medal contender for Sunday's 50km race, after coming eighth in the Olympic skiathlon two weeks ago.
Dürr, 26, is the fifth athlete to have tested positive at the Sochi Olympics. But his is the first serious doping offense, with the other four cases involving minor stimulants that can be found in food supplements.
Early on Sunday, it was announced that Latvian ice hockey player Vitalijs Pavolovs had tested positive for the banned substance methylhexanamine. This came after German biathelete Evi Sachenbacher-Stehle, Italian bobsledder William Frullani and Ukrainian cross-country skier Marina Lisogor failed doping tests, also for minor stimulants.
Austria has been involved in major doping affairs at two of the last three winter Games.
Russia to the fore
Meanwhile, host country Russia is at the top of the medals table, just in front of Norway, with three golds in total to be won on the final day on Sunday.
It clinched this position on Sunday morning with a clean sweep in the men's 50km cross-country men's mass start.
Alexander Legkov won the race by a margin of just 0.7 of a second, with compatriots Maxim Vylegzhanin and Ilia Chernousov finishing second and third.
Russia had had a disappointing cross country competition until Sunday, winning just two silvers in team events.
And Russia went on to bolster its lead with a victory in the four-man bobsleigh.
Alexander Zubkov held onto his slender overnight lead to come in first by nine hundredths of a second ahead of Latvia's Oskars Melbardis. American Steve Holcomb, the 2010 champion, won bronze.
The men's ice hockey final between Canada and Sweden will bring down the curtain on the action at the Winter Olympics on Sunday afternoon, followed by the closing ceremony.
tj/hc (dpa, AP, Reuters)