Greene – the reigning world, European and Commonwealth 400m hurdles champion – has upset some of his American rivals, chiefly Bershawn Jackson, with some incendiary off-season comments.
And his coach Malcolm Arnold let slip earlier this month he'd spent time sidelined from training following a knee operation.
However, Greene insists his secrecy had nothing to do with wanting to surrender a psychological London 2012 advantage.
“It wasn't that I didn't want to give any of my rivals an advantage by not revealing it (his injury) because I knew all my British rivals knew anyway,” he said, after advancing through his heat at the Aviva 2012 Trials in Birmingham.
"I didn't want to have to answer loads of questions when I was dealing with a tough situation myself at the time.
“So it was just easier to keep it under wraps. We seem to have come out the other side now and turned the corner."
But defending champion Nathan Woodward - Greene competed over the flat 400m last year - insists he won't be letting his title go without a fight, especially as five British athletes have the Olympic A standard qualifying time.
He went fastest in 50.34 secs but insists he will still need to find more in the final.
“I’m definitely peaking at the right time,” he insisted.
“After a slow start I’m more and more coming into my season, so I’m ready now.
“It's going to be a quick final. I think the field could even be stronger than a European final because this event has such strength in depth at the moment in the UK.
“It wasn’t overly quick but with it being a heat I was just trying to conserve as much energy as I could.”
Elsewhere, Olympic champion Christine Ohuruogu comfortably progressed through her 400m heat and was the fastest qualifier ahead of three-time national champion Lee McConnell.
And Marilyn Okoro, who is regaining the sort of form that made her British number one heading into the Beijing Olympics, was quickest in 800m qualifying in the absence of former world bronze medallist Jenny Meadows, who is recovering from an Achilles injury.
Mo Farah produced an exhibition winning run in the 1500m heats - an event he doesn’t even plan on running at London 2012 with the 5,000m, in which he is world champion, and 10,000m, where he is looking to upgrade world silver, his priorities.
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