Let's be honest. Two hours of a smarmy Englishman in conversation with a rambling, self-important politician has all the appeal of waterboarding. Yet 'Frost/Nixon', based on 1977's televised interviews with the former US prez, comes out swinging. It has all the brutality, tension, low blows (and even sweat) of a boxing match ? although not a single punch is thrown. This sparring is strictly verbal, baby. But it's between two actors in their prime.

Michael Sheen is TV presenter David Frost ? lover of the ladies, rolling with the rich, swinging with the stars. Austin Powers with a microphone and camera crew, to journalists he's a frivolous entertainer rather than a colleague, to the public his fruity accent and catchphrases are there to be mimicked ? often to his face.

So, despite the size of his mojo, he just can't get no respect. And, despite the slapped-on smile, that really stings. The solution, the shameless self-promoter decides, is a series of hard-hitting conversations with the disgraced Richard Nixon. Instant credibility and, based on the millions around the world who watched Tricky Dicky's resignation, a huge global audience.

Frank Langella is the unrepentant man who famously declared "I am not a crook" while dodging the fallout from the Watergate scandal, and defiantly flashed the V-for-victory sign as he left office for the last time in '74. Living the life of a pensioner, playing golf, penning his memoirs, and still shunned by Washington three years after stepping down, he agrees to the proposed chats. For the $600 000 on offer and the opportunity to find redemption. Nixon too considers the eternal showman a lightweight, a pushover who can be bullied with superior intellect. But with his own money and reputation at stake, Frost ? equal parts desperate and determined ? is prepared to punch above his weight.

Both actors, reprising the roles they originally brought to life on stage, are quite simply sublime. Sheen, criminally undervalued as Tony Blair in 'The Queen', subtly reveals the doubts that surface behind the grinning mask. Langella, all droning voice, adds a powerful roar to the wounded lion cliche. In extreme close-up, using just his eyes and sweaty upper lip, his face is a portrait of arrogance, conviction, even hurt.

A single unexpected late-night telephone conversation reveals more about Richard Millhouse Nixon than five years in office did, underlining the depth of his performance ? as well as the talent of screenwriter Peter Morgan who, with efficient direction from Ron Howard, turns his wordy stage play into a 'Raging Bull'.

Politics never seemed so alive.