David Beckham and Matthew Terry launch the battle of the pants

Our thoughts turn to Valentine's Day, and in a pleasant diversion from red-foil-wrapped chocolate hearts, it is turning out to be a good week for men in pants. Pants, so we are encouraged to believe, being the most romantic item to buy for the man in your life this 14 February.

During Sunday night's Super Bowl a certain Matthew Terry, the beautiful and almost disgustingly ripped star of the new Calvin Klein underwear advert was introduced to the world, making the 21-year-old former personal trainer from Ohio the most tweeted-about man on the planet for half an hour. Justifed? You can decide here, and here

This morning at 9am, H&M set its own man in boxers loose online, at noon said man will be tweeting from @HM and by tonight he will be viral on every media platform available, including a full 90-second advertising slot during One Born Every Minute on Channel 4. He is, of course, the nation's favourite underpant model, David Beckham, who is promoting his "Bodywear" line with the Swedish retail giant in a very entertaining and knowing mini-movie directed by Guy Ritchie.

In the ad, we see our hero locked out of his Beverly Hills home as the missus takes off in the Range Rover on the school run, his dressing gown (presumably with his house keys in the pocket) trapped in the car door. So off David runs through the back gardens of his disbelieving neighbours' mansions; he jumps through bushes, dives into pools, vaults over paparazzi and runs rhythmically fast in the manner of a top footballer chasing a ball. You get the metaphorical picture. I'll let you enjoy the rest.

Unlike the old-school man as machine approach of the Calvin Klein advert by the New York agency Baron + Baron, H&M's in-house approach is brilliantly apposite to the gilded-cage lifestyle we imagine David Beckham leads, with cameraphones at every turn. Except through Ritchie's lens, Beckham, self-deprecating smile at the ready, wears a pair of khaki ribbed trunks (only £9.99), which need a little flick at the left buttock every time he embarks on a new adventure.

This article was written by Melanie Rickey, for guardian.co.uk on Wednesday 6th February 2013 11.35 Europe/London