Saracens got out of the blocks fast with two converted tries in the opening 10 minutes from Argentina flanker Juan Martin Gonzalez – making his 50th league appearance – and Tobias Elliott.
Leicester hit back with two of their own from the powerful Solomone Kata, who shrugged off Elliott’s attempted tackle, and Hamer-Webb after a lovely ball by Steward.
With Saracens employing a 6-2 bench split, the loss of centre Olly Hartley early on to an arm injury and the temporary removal of Tobias Elliott to an HIA, meant England flanker Ben Earl was sent on as a centre.
But it made little difference to Saracens’ fluid attack with Elliot Daly, back after a broken arm, crossing out on the left after some lovely interplay.
Leicester responded in the second half with two more tries from Hamer-Webb, both involving impressive new signing Aaron Wainwright in the build-up.
In between Earl, in a more familiar back row role after the withdrawal of Alfie Barbeary at half-time, thundered over for Saracens from Williams’ flat pass.
Leicester took the lead after a nice piece of vision from scrum-half Jack van Poortvliet with a deft chip through for Radwan to score. And as Billy Searle was lining up the conversion, referee Ian Tempest reached for a 20-minute red card after Isiekwe’s shot on Steward in the build-up.
But 14-man Saracens regained the lead with a try from wing Segun after a pinpoint cross-kick by Daly, and after Leicester replacement James Thompson had burrowed over to restore the Tigers lead, Segun struck again wide out on the left with seven minutes left.
Leicester: Steward; Radwan, Kata, Woodward, Hamer-Webb; Searle, van Poortvliet (capt); Vunipola, Moli, Heyes, Carnduff, Henderson, Wainwright, Reffell, Cracknell.
Replacements: Thunder, Haffar, Hurd, Thompson, Moro, Whiteley, Bailey, Hassell-Collins.
Saracens: Daly; Elliott, Tompkins, Hartley, Segun; Burke, Williams; Mawi, Dan, Street, Itoje (capt), Tizard, Isiekwe, Gonzalez, Barbeary.
Replacements: Clarke, Brantingham, Clarey, Sodeke, Michelow, Earl, C Bracken, Malins.
Referee: Ian Tempest