The biggest danger to America is not refugees but the man orchestrating their castigation from the White House

The only escape route from this horror, said the friend next to me on the sofa at noon today, is if this final set goes to 40,000-40,000. That way, we won’t have to return to the real world until after the next US election.

In the event, this fantastical piece of sporting nostalgia ended in Roger Federer’s favour within minutes. But for the preceding three and a half hours, you could almost persuade yourself that you’d slipped through a tear in space-time, and gone back eight years to the last time the Fed and Rafael Nadal duked it out over five sets for the Australian Open title.

The date of that one, won by Rafa, feels viciously poignant today. On 1 February, 2009, Barack Obama had been in the White House for under a fortnight, and the echo of his sublimely humane inauguration address had the world light-headed with hope.

Not even a fortnight after Donald Trump mistook his inauguration speech for a Mussolini tribute act, it would take the Hubble telescope on steroids to detect a slither of optimism. The banning of residents and passport holders from, not to mention people merely born in, almost every Muslim nation with which Trump has no business relationship creates a heavier, more broodingly dark atmosphere than anyone too young to remember the Cuban Missile Crisis will recall.

The stories of heartrending exclusions already stack up. You may have heard of Iraqi interpreters who for a decade worked in great danger for the US military, but whose long-awaited and heavily vetted visas were revoked on Saturday; of green card holders with a clear legal right to US residency denied re-entry after visiting sick relatives; of the Iranian director who can’t attend the Oscars at which his film will be a nominee.

You won’t be aware of a friend’s father who missed the Roger-Rafa classic because he was flying to the States. A British national with no other passport, he was once such a heroic critic of the Ayatollahs that, after he fled Tehran, they sent death squads to London to assassinate him.

When he arrived at Heathrow this morning, he had no idea whether, by dint of being born in Iran, he would be detained and sent home on suspicion of being a puppet of the regime which so assiduously tried to kill him.

So anyone unsure whether the mantle of office would diminish Trump’s megalomaniacal brutishness has their answer. He told us what he would do, and lo, verily, it hath come to pass – albeit the reality is worse than feared. Who thought that a Muslim ban widely dismissed as no more than campaign histrionics would extend to green card holders? But Trump is the greatest limbo dancer in political history: however low he sets the expectations bar for himself, he finds the way to squeeze beneath it.

Evidently he is racing towards destructive war with those parts of the media that see no distinction between a whopper and an alternative fact, and also with the judiciary. The ban’s rejection by a federal judge, Ann Donnelly, can only be the prelude to a Supreme Court case. If the Supremes declare it unconstitutional, would that restrain his dictatorial instincts or inflame them? Would civil unrest on a scale unseen since the 1960s race riots temper his lunacy or exaggerate it? Is he capable of pragmatism, in other words, or does the seam of messianic self-regard run too deep to be penetrated by external pressures?

While we shiver in wait for the answer, innocent lives are being destroyed by what the Somali-born Mo Farah called ignorance and prejudice. It does more than rend the heart. It fills it with an ominous bleakness the like of which few have experienced.

Although the pervasive gloom leaves little room for other emotions, I can’t deny a pang of sympathy for Theresa May. Fair enough if you decline to share it after her wretched efforts to be silent about the Muslim ban. But try to imagine the agony, for a fundamentally moral human being, to find herself squeezed between the rock of Trump’s wickedness and the hard place of needing his indulgence on the trade deal front.

One minute she’s holding his weeny hand, and then she’s ingratiating herself with Turkey’s tyrannical President Erdogan – the next she’ll be kneeling before the Chinese. At this rate, she’ll be zigzagging between the nastier central Asian republics and Robert Mugabe before Roger and Rafa make their Centre Court returns in late June.

May is neither callous nor stupid. She knows that for evil to triumph, all that’s required is for good women to do nothing. She also knows how desperately economic growth will depend, post-Brexit, on trade relations with regimes that show a nauseating disregard for human rights. The tension between these competing bits of knowledge might be powerful enough to break a sensitive soul in two.

But there are stronger magnets for our pity than a PM who degraded herself by taking so long to criticise Trump’s lurch towards paranoid fascism, and being so pusillanimous about it when she did. Some are separated indefinitely from loved ones, some have been rendered stateless like Tom Hanks in The Terminal and others may be at risk of torture and death in countries they had the requisite visas to flee. Since all were exhaustively vetted, only one character in this macabre tale poses a lethal threat to the United States. That’s the one hell bent on destroying the Constitution he took an oath to protect so recently that Andy Murray was favourite to win the Australian Open at the time.