Wales wing George North will benefit from his five months on the sidelines, says captain Sam Warburton.
North has not played since March because of concussion, but could return for Wales' World Cup warm-up match against Ireland on 29 August.
The 23-year-old is back in full training with Wales, and Warburton thinks he will be revitalised.
"It would be a huge blow if we lost him, but I think it's a bit of a blessing the break he's had," he said.
"He came on the scene as one of the best wingers in the world straight away, and he has such high expectations from himself and people externally.
"So I think it's been good for him over the last few months. I think he'll come back hungrier than you've ever seen him before."
North saw a consultant neurosurgeon after being knocked unconscious during Northampton's Premiership win over Wasps in March - the third time North had suffered a blow to the head in six months.
But after missing the final 10 weeks of last season, North played a full part in a contact session as Wales trained in front of about 5,000 fans in Colwyn Bay on Tuesday.
He was not risked in Saturday's warm-up defeat by Ireland in Cardiff and is being continually assessed. The Wales backroom team are pleased with his progress.
And Warburton believes his fellow British and Irish Lions player will be at his best when Wales begin their World Cup campaign against Uruguay on 20 September.
"He's been training really well from day one," added Cardiff Blues flanker Warburton.
"Physically he's a freak and I never had any doubt he was going to miss the World Cup.
"He's one of our players who has got the X-factor.
"Every now and then you need a little break from the game, and I think this break will be good for him."