Mako Vunipola remains a major doubt for England's New Zealand tour after being ruled out of Saturday's Aviva Premiership final with knee trouble.
The 23-year-old suffered knee damage in Saracens' 23-6 Heineken Cup final defeat to Toulon in Cardiff last weekend.
England's second set of tourists fly out to New Zealand on Monday, after Saturday's Premiership final between Saracens and Northampton.
Vunipola's failure to recover in time for the league showpiece suggests he now faces a fight to take any part in England's three-Test tour.
The former Bristol front-rower's knee problem further deepens England's injury concerns at loosehead, with Joe Marler suffering a hip complaint.
England called up Bath's Nathan Catt as late cover for Marler in the initial group of tourists that flew out to New Zealand on Tuesday.
Wasps' three-cap loosehead Matt Mullan will now start England's first Test against the All Blacks in Auckland on June 7 unless either Marler or Vunipola make a rapid recovery.
Head coach Stuart Lancaster received more positive news from Northampton, with hooker Dylan Hartley fit enough to take a seat on the Saints bench for the Premiership final.
The 28-year-old has not played for two months with shoulder trouble, and his return indicates he will be ready to fly out to New Zealand on Monday.
Saints prop Alex Corbisiero will not tour this summer having only just recovered from long-term knee trouble, and Leicester hooker Tom Youngs has been handed compassionate leave while his wife receives treatment for an illness.
England must compete in the first Test with the All Blacks without their Premiership final contingent, leaving as many as 15 players unavailable.
The International Rugby Board scheduled all summer series to start just seven days after the English clubs final owing to a technicality of ruling the May 31-June 1 weekend as the official first weekend of June.
Had the IRB deemed June 7-8 the official first weekend of the month, England's Test series against the All Blacks would not have kicked off until June 14.