The 34-year-old -- a four-time Olympic gold medallist and five-time world champion having achieved the 5000m and 10000m double twice in both sporting showpieces -- said he could have done little about his medical records being hacked by Fancy Bears and then leaked to the press last week.
"Other things don't distract me. I'm only in control of my legs. Never will I fail a test," said Farah.
"I run year after year with joy and there's not much more you can do.
Whilst Farah posted an impressive warm-up run for the world championships and his track swansong in London in three weeks' time, there were others too who made statements of intent.
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Jamaica's 100m and 200m women's champion Elaine Thompson won the 100m, coming from behind to edge out her great rival Dafne Schippers despite wearing shoes which resembled trainers.
"I do have on spikes but they are very petite. They are built especially for me and made lighter," said Thompson.
There was a cracking race in the women's 100m hurdles, with world record holder Kendra Harrison pushed the whole way by Australia's Sally Pearson, who experienced her greatest moment on the same track in 2012 by taking Olympic gold.
"She (Pearson) really pushed me and I hit a few hurdles as I felt her next to me," said Harrison, who made it 21 successive wins.
For Pearson it was a welcome return to form after injury blighted the past two years.
"I knew I was in good shape. This is far out! I am really excited I've been able to prove myself."
- Merritt returns to form -
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Aries Merritt suggested he could well be a title contender in the men's 110m hurdles at the worlds, just two years after undergoing a kidney transplant as the 2012 Olympic champion won in his season's best of 13.09sec.
"I won Olympic gold here and I couldn't be more thrilled to be running into form at the right time," said Merritt.
American great Allyson Felix ran an eye-catching 400m to time 49.65sec, the fastest time in the world this year on what was her first appearance of the season in the Diamond League.
"I just so love the sport and I am going to keep fighting hard."
Nijel Amos threw down the gauntlet to the 800m title contenders when the Botswana athlete ran the fastest time in the world this year in 1min 43.18sec on the track where he won Olympic silver behind David Rudisha in 2012.
"I have just kept the faith and worked hard and now I hope to see the fruits realised in August," said Amos, who has battled back from injuries.
"That is definitely the last time on the track," said Weir.
"This is the finale that I wanted -- it is amazing to have my family here with me, especially my kids who don't come to many races."
There was a world record in the rarely competed one- kilometre walk on its first outing in the Diamond League -- Tom Bosworth recording a time of 5min 31.08sec.
The British national anthem also rang out -- an oddity in itself at a Diamond League meeting -- as the men's 4x400m relay quartet from the 2008 Beijing Olympics received bronze medals.