The British Army and a Help for Heroes squad are also in action this year alongside the Guinness Premiership clubs and invitational teams the White Hart Marauders and Samurai 7s.
The 16 teams will battle it out during a day of fast-flowing rugby to be crowned Middlesex champions.
Charitable proceeds of the day go to the RFU's Injured Players Foundation and the PRA's Benevolent Fund. The Help for Heroes charity will also receive cashback from their ticket sales.
The first game kicks off at 10am and will be the opening match of a memorable season as Twickenham Stadium celebrates its centenary.
First-round draw and match order:
British Army v Bath Rugby
Gloucester Rugby v London Irish
White Hart Marauders v Harlequins
Saracens v Worcester Warriors
Samurai 7s v Northampton Saints
London Wasps v Leeds Carnegie
Newcastle Falcons v Leicester Tigers
Sale Sharks v Help for Heroes
Tickets for the Middlesex Sevens are £10 for adults and £5 for juniors. Type 'legends' to get the special offer available at www.MiddlesexCharitySevens.com or telephone 0871 871 0777.
