Ulster have been dealt a major blow ahead of the new season with their star Ireland wing Jacob Stockdale sidelined by injury.
Stockdale, Six Nations player of the tournament earlier this year, faces six to eight weeks out.
Ulster tweeted: "Jacob Stockdale suffered a grade 2 hamstring strain in training and is expected to return to play in 6-8 weeks."
INJURY UPDATE 👎 | Jacob Stockdale suffered a grade 2 hamstring strain in training and is expected to return to play in 6-8 weeks pic.twitter.com/foRu7K2jtR— Ulster Rugby (@UlsterRugby) August 13, 2018
Ulster launch their Guinness PRO14 campaign against the Scarlets on September 1.
The 22-year-old scored a Six Nations-record seven tries in last season's tournament, and is a key member of the Ulster squad.
An eight-week absence would see Stockdale available again just before the Heineken Champions Cup begins in October.
Ulster are in the same Champions Cup group as Leicester, Racing 92 and Scarlets.
Ulster star Stockdale has made an outstanding start to his international career, scoring 11 tries in 11 Tests.
He played a pivotal role when Ireland swept to the Six Nations title in Grand Slam fashion five months ago, and he was also part of their successful Australia tour earlier this summer.
Ireland's opening Test of the 2018-19 season is against Italy in Chicago on November 3, which is followed by Dublin appointments with Argentina, world champions New Zealand and the United States.