Saracens could be without England back-row Billy Vunipola for the first month of the Premiership season as he recovers from shoulder surgery.
Former Saracens centre Tim Streather retires from rugby union on medical advice with a persistent knee injury.
Premiership champions Exeter will begin their title defence at Gloucester when the 2017-18 season starts on 1 September.
Saracens re-sign Australian prop Kieran Longbottom on a one-year deal from Premiership rivals Sale Sharks.
Audio & Video
Wales full-back Liam Williams plays his last game at Parc y Scarlets on Saturday before leaving Scarlets for Saracens, so we pick out some of his best moments for the Llanelli-based region.
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What's on BBC Sport this week
This week's sport on the BBC includes the Challenge Cup final from Wembley, England v West Indies in the second Test at Headingley and the Belgian Grand Prix.