Boris Johnson will make his G7 closing speech five minutes after England kick off their first game in the Euros on Sunday.
The Three Lions take on Croatia in the Group D match from 2pm on Sunday. Johnson's speech is scheduled for 2.05pm.
The PM, known as a rugby and cricket fan, has insisted he also follows football, but a series of slip ups have cast doubt on his claim.
As host of the summit he could decide when press conferences are scheduled.
Johnson scored an own goal at Prime Minister's Questions this week when by forgetting Wales would appear at the tournament – just the third time in the Dragons' history they have been involved in a major contest.
The PM wished "all the very best to Scotland and England", missing out Wales before adding, after a brief pause: "...and all the Home Nations who may be playing."
In 2014, while London mayor, Johnson was caught on camera tripping up a child during a match outside City Hall.
Prior to that, in 2006, he took to the pitch for an England v Germany “Legends' Match" and ran headfirst at waist height into former Stuttgart defender Maurizio Gaudina, grounding him.
In 2015 he was asked about his football allegiance but gave a non-committal answer, telling reporters he supported "all of the London teams", refusing to name just one.
When asked about the timing of Johnson's speech, a Number 10 spokesperson said: "It is looking likely there will be a clash I'm afraid, but we will do our best.”
World leaders including US president Joe Biden, German chancellor Angela Merkel, and Canadian PM Justin Trudeau arrived in Cornwall this week for the G7 summit, greeted by Johnson and wife Carrie with their one-year-old son Wilfrid.
US first lady Dr Jill Biden and Carrie Johnson were pictured enjoying a walk on the beach and dipping their feet in the sea with baby Wilfred on Thursday.
Johnson opened the first session of the summit on Friday by asking his fellow leaders not to repeat mistakes from prior crises where economic recovery was uneven, and urged G7 nations to focus on building back greener and more equal.
“We need to make sure that we don’t repeat some of the errors that we doubtless made in the course of the last 18 months or so,” Johnson said. “I think there is the potential to generate many, many millions of high-wage, high-skill jobs.”
Johnson said people want to see that countries are working on “building back better,” repeating a much-used slogan of his.
“And building back greener and building back fairer and building back more equal and how shall I — more gender neutral, in perhaps a more feminine way, how about that, apart from anything else,” he said.
Watch: The G7 summit kicks off in Cornwall