Wasps could be without playmaker Jimmy Gopperth for up to nine months after anterior cruciate ligament surgery.
The 35-year-old, who can play fly-half or inside centre, was injured in a pre-season friendly against Connacht, and will miss six to nine months.
Gopperth played 22 games last season at inside centre and stand-off.
All Blacks fly-half Lima Sopoaga is unlikely to arrive in time for Wasps' away Premiership opener against Worcester on 1 September.
Gopperth's injury leaves director of rugby Dai Young with a quandary following the departures of Danny Cipriani to Gloucester and Kyle Eastmond to Leicester.
Full-back Rob Miller could deputise or Bristol's Billy Searle who was signed this summer, but Gopperth, who won a clean sweep of player awards in 2016-17 as Wasps reached the Premiership final, will be difficult to replace.
He has scored 1,290 points in six Premiership seasons with Newcastle and Wasps, either side of a spell at Leinster.
Meanwhile, prop Jake Cooper-Woolley and hooker TJ Harris face lay-offs with biceps injuries.
Cooper-Woolley will be out for up to eight weeks, while Harris is expected to return within six weeks after surgery, but will miss the start of the season.
Source: BBC Rugby Union News