England international second row Steve Borthwick will make his Premiership debut for Saracens on Saturday.
Former Bath lock Borthwick, who captained England on tour in New Zealand three months ago, makes his Saracens bow alongside former Wales skipper Michael Owen, who also joined the club this summer.
And new Sarries boss Eddie Jones fields them in a powerful pack that features New Zealand second-row forward Chris Jack playing at blindside flanker for the Twickenham clash against Harlequins.
Behind the scrum, injuries sideline back-three players Richard Haughton and Brent Russell, although both players could return against Sale Sharks next week.
Jones said: "We faced some tough selection choices following all the hard work the players have put in over pre-season.
"We've worked hard to improve as a team and as individuals, and we have moved forward as a group, but the real test starts on Saturday against Harlequins.
"Steve Borthwick and Michael Owen have quickly settled into the team and have added great strength and depth to the squad. Both have already demonstrated their leadership abilities on the pitch.
"Chris Jack has been one of the best second-rows in the world for many years, but we felt he needed a challenge to improve as a player, so he has been selected in the back-row after featuring in that position during pre-season.
"It is not necessarily a permanent switch, but it's something we believe will help the composition of the team and also allow us to get the best out of him."
England Under-20s head coach Martin Haag was full of praise for his World Rugby Under-20 Championship-winning side after Harry Mallinder inspired them to a 45-21 win over their Irish counterparts and a third title in four years.