For months Donald Trump mocked Joe Biden for his cautious campaigning during the coronavirus pandemic.
But with the president in quarantine from Friday after testing positive for Covid-19, his Trump train derailed for now, Democratic challenger Biden has the stage to himself one month before Election Day.
It is too soon to predict how Trump's diagnosis could impact the White House race, already the most turbulent US presidential battle of modern times and one repeatedly upended by history-making events.
But the irony of the latest twist in the septuagenarian showdown was lost on no one.
After all, just Tuesday night Trump doubled down on his ribbing of Biden for taking too many virus precautions.
"He could be speaking 200 feet away from you, and he shows up with the biggest mask I've seen," the 74-year-old Republican incumbent sneered.
In the early months of the pandemic, as Biden, 77, remained isolated in his Delaware home, Trump belittled "Sleepy Joe" for "hiding" in his basement -- a charge his supporters lapped up and repeated ad infinitum.
But on Friday, Trump was the one hunkered down, receiving treatment at the Walter Reed military hospital after his positive diagnosis.
Biden mostly has been meticulous about avoiding crowds and wearing masks in public.
But he was on stage with the president during their off-the-rails debate, three nights before Trump's diagnosis.
Biden and his wife were quickly tested for the virus Friday. Minutes after their results came back negative, his team fired up the campaign jet and Biden flew to battleground Michigan, a key Rust Belt state that Trump claimed in 2016.
The somber appearance at a labour union in Grand Rapids had only a few dozen people present and no visible personal interaction with voters.
But the message was clear: Biden is not letting Trump's diagnosis upend his own campaigning, which has ramped up recently including Wednesday's whistles top train tour across Ohio and Pennsylvania.
Michigan voters who lined the road outside Biden's event offered their own take on recent developments, with one woman holding a small sign reading "Masks work."
Biden's speech, which he delivered wearing a face mask, focused on the economy but also touched on the day's bombshell headline.
