Wales assistant coach Neil Jenkins says captain Matthew Rees will miss the first World Cup warm-up game against England but is confident he will be fit for the World Cup in September.
"Hopefully he'll pay a part in the other two [warm-up] games," Jenkins said on Tuesday.
It emerged on Monday that Rees was having treatment for a neck injury.
Blues flanker Sam Warburton will skipper Wales against England on Saturday at Twickenham.
Jenkins said he is confident Rees will be fit for the World Cup, adding: "He's obviously had an injection and we're just going to see where he's at at the start of next week.
"And hopefully we can get him back on the pitch as soon as possible and take some part in these games that are remaining after Saturday.
"So I think Matth's going to be fine [for the World Cup] and it's just making sure he comes through this and gets back on the pitch as soon as possible."
On Monday Gatland told the media: "Matthew has had a bit of a neck problem for a few weeks.
"An operation is a definite possibility but we are hoping it definitely won't be before the World Cup. If he doesn't improve, he may need something after the World Cup.
"There is a bit of nerve pressure, and we're hopeful the injections will help. It is mainly affecting him when he is trying to sleep."
Gatland had said Scarlets front-rower Rees was becoming frustrated because he had not been able to do much during the past few weeks. The squad has held two intensive training camps in Poland.
Warburton captained Wales in their 28-31 defeat to the Barbarians in June, after British and Irish Lions hooker Rees led Wales through the 2010-11 season.
Wales face England first at Twickenham then in Cardiff, on successive Saturdays, before a Millennium Stadium match against Argentina on 20 August.
Gatland is to name his World Cup squad on 22 August and their first match of the tournament is against defending champions South Africa on 11 September.