Greece's world indoor high jump champion Dimitris Chondrokoukis pulled out of the Olympics on Thursday after testing positive for an anabolic steroid, with both the athlete and his father denying doping.
Later that same day, it was confirmed that Hungarian discus thrower Zoltan Kovag would miss the Games after an earlier positive test was upheld by the Court of Arbitration for Sport. He was banned for two years.
I was speaking to former 400 metres star Roger Black and he said we've had six positives so far as they test athletes before it all starts.
The Greek athlete is world indoor champion, and probably their best chance of a medal in athletics, so it's not insignificant.
Of course it's not great news, but hopefully they will catch the cheats before the events start and we can have a clean Games.
I feel the improved testing will lead to the cheats being caught out, and hopefully to clean British athletes winning medals.
Actually, it's great news for clean athletes, and Team GB — we have a European champion and a medal contender in Robbie Grabarz in Chondrokoukis's event, so you'd have to say it's a boost for him.
Obviously you never want this kind of news — but it's testament to improved biometric testing, and the detection of masking agents, that we can find people who cheat so effectively.
Former javelin world record holder and twice Olympic silver medallist Steve Backley will be an expert consultant for Eurosport-Yahoo! during the London 2012 Games.