English rugby union's traditional season curtain-raiser takes place on Saturday when Twickenham stages the Middlesex Sevens.
The tournament, first held in 1926, this year features six past winners, while England, Scotland and Wales all appear under charity banners in an important rehearsal for the autumn's Commonwealth Games.
England's Help for Heroes squad, under the guidance of national sevens coach Ben Ryan, face a tough first round encounter against Saracens, who won a recent sevens tournament involving Aviva Premiership clubs. The Scottish squad will do well to overcome the British Army - Middlesex Sevens champions in 2001 and 2004 - while Wales tackle a powerful Harlequins unit that features England quartet Ugo Monye, Danny Care, Nick Easter and Chris Robshaw.
"The competition will be the start of our build-up to a busy season in sevens with the Commonwealth games just around the corner," said Wales coach Paul John.
"But there are some top English Premiership clubs in the tournament and sides like Kenya, Samurai and the British Army, who are regulars on the circuit.
"England will also be strong, as always, having gone down the 100% professional route with their players. They will be well-prepared in front of the Twickenham faithful."
Title holders London Irish, complete with the likes of Delon Armitage, Paul Hodgson and Sailosi Tagicakibau, open up against Leicester, while Wasps - spearheaded by renowned sevens exponents Tom Varndell and David Lemi - face Newcastle in the two all-Premiership first round ties.
Newcastle lifted the trophy in 2007, and a strong Falcons squad includes England sevens internationals Micky Young, Rob Vickerman and Charlie Amesbury.
"There is plenty of talent in this Falcons group, and it promises to be an exciting tournament. The standard of competition will be high," said Newcastle coach Mark Laycock.
First round draw (start 1030): London Irish v Leicester, HFW Wailers v Exeter, Wasps v Newcastle, Saracens v England's Help for Heroes, British Army v Scotland's Thistle Trust, Kenya v Leeds Carnegie, Wales Amser Justin Time v Harlequins, White Hart Marauders v Samurai International.