Newspaper headlines: 'Modern life killing children' and 'Calais carnage'
Theresa May's debut on the global stage - with a message that Britain is open for business post-Brexit - prompts reports that Britain and Australia are poised to sign a new free trade deal.
The Sunday Telegraph says the prime minister will meet her Australian counterpart, Malcolm Turnbull, on Monday at the G20 summit in China.
The paper says they will shape the broad outline of what would be Britain's first new trade agreement after people voted in June to leave the European Union.
The Telegraph says she is also expected to "explore further trade opportunities" in talks with US President Obama and the Indian prime minister.
The Sunday Express believes an "exciting future" lies ahead and goes on to say that the deals Mrs May strikes at the G20 conference will be "the building blocks for a more prosperous and autonomous United Kingdom".
The Observer sets out what it calls a guide to who Theresa May will want to "hug close or avoid" at the summit in China.
It says Britain's decision to leave the EU has made the G20 "a meeting of seminal importance" for Mrs May.
The paper's political editor, Toby Helm, says a bilateral meeting with China's president, Xi Jinping, will arguably be her "sternest test", especially as she has delayed a decision over the Hinkley Point nuclear power station, which the Chinese are set to invest in.
There's also advice for Mrs May on how to deal with some of the world leaders she'll be meeting, such as Russian President Vladimir Putin, in the Sunday Telegraph.
'Undress under duvet'
Theresa May has been warned to get "undressed under the duvet" while she's in China, according to The Sunday Express, to avoid being snooped on by Chinese spies at the G20 summit.
The paper also says aides to the prime minister have been warned to beware of so-called honey traps.
It reports that the extraordinary precautions were part of security advice issued to Mrs May and her staff before their visit to China.
The Sunday Mirror reports that even before the start of the summit, Chinese hackers had already targeted five EU foreign ministries.
It says staff from the Czech Republic, Portugal, Bulgaria, Latvia and Hungary were tricked into downloading malicious files which hijacked their computers.
Thatcher 'opposed Brexit'
More than three years after Lady Thatcher's death, The Observer carries a claim that she "would not have supported Brexit", or holding an in/out referendum on the EU.
Lord Powell - who was the former prime minister's longest-serving foreign police adviser - tells the paper that "of course she got fed up" with the EU.
But he says Margaret Thatcher "never had any truck" with referendums and wanted to change the EU from within.
The paper adds that his comments will anger anti-EU Tories, who it says "portray themselves as having completed the work of their political heroine".
They claim she set the UK on the road to Brexit with a speech in 1988 warning of the dangers of closer EU integration.
Days before the opening of the Rio Paralympics, the Guardian reports that UK Athletics is to launch an inquiry into the classification of Paralympic track and field athletes.
The paper says there have been claims that some athletes have been allowed to compete against people who are significantly more disabled, resulting in a boost to their medal chances.
The Sunday Times says top British paralympians feel unfairly treated amid claims of rules being abused to bring in less disabled athletes in a ruthless pursuit of gold.
The Times calls it "The betrayal of Team GB".
'Carnage in Calais'
"Carnage in Calais" is the headline on the front of the Mail on Sunday, as it claims that migrants from the camp, known as the Jungle, are using a "deadly new tactic" in their attempts to get to the UK.
The paper says a team of its journalists narrowly escaped death last week when three migrants threw a log at their car, forcing it into the path of a 38-ton lorry.
Alongside dramatic pictures of a smashed car and injured journalists, the paper says "ruthless gangs" are causing cars to crash, so they can sneak on to lorries caught up in the resulting tailbacks.
The Mail says it has alerted Home Secretary Amber Rudd to what is happening and that she is extremely concerned.
Writing in the paper, the Conservative MP for Dover, Charlie Elphicke, warns that someone could be killed unless the French authorities "tackle the anarchy".
A British warship is on its way to Libya to intercept and arrest people smugglers, according to the Observer.
It says HMS Diamond is being deployed as part of an EU crackdown on the smugglers who are aiding record numbers of migrants trying to cross the Mediterranean to Italy.
The paper reports that at least 100,000 men, women and children have crossed the sea from north Africa since the start of the year, but fewer than 100 traffickers have been arrested.
More than 3,000 people have drowned, it says.
"Modern life is killing children," declares the Sunday Telegraph, as it reports that the number of children diagnosed with cancer has leapt by 40% in less than two decades.
The paper says there are now 1,300 more cancer cases in younger people, per year, than there were in 1998, when the first figures were published.
Experts are blaming pollution, fast foods and gadgets, such as mobile phones and tablets, as factors in the increase.
A spokesman for the charity Children with Cancer UK tells the Sunday Mirror that "it's an epidemic" and Alasdair Philips warns: "We are losing the battle against childhood cancer."