England backs coach Andy Farrell told a news conference on Tuesday that criticism of Gatland for allowing the talismanic fullback to play in the win against Italy on Saturday was unfair.
Welsh hopes of surviving a group containing England, Australia and Fiji took a massive blow when Halfpenny, scorer of 508 points in 62 tests, went off on a stretcher in Cardiff during a match in which scrumhalf Rhys Webb was also injured.
Despite Halfpenny’s recent history of injuries, Gatland declined to wrap the kicking king in cotton wool and paid a heavy price.
“Players need game time,” said Farrell. “We’ve been training for more than 10 weeks and the reason you train is to make sure you can play well, and where it matters, on the battlefield of an international arena.
“There is no substitute for putting yourself in those situations and you have to have these warm-up games otherwise you become completely undone.
“Injuries are part and parcel of the game and we feel very fortunate we’ve come through unscathed,” added Farrell.
“Leigh himself would have wanted to play, I have no doubt about that. I know his attention to detail is spot on and he would have wanted to get out on the field to feel good about himself. I feel very sorry for both of the Wales players.
“He would be a big loss to any side, and for the competition, because we want to see the best out there.”
Wales confirmed on Tuesday that scrumhalf Webb was out of the World Cup too after injuring his foot against Italy.
They are also without another first-choice back, Jonathan Davies, who suffered a serious knee injury in March.
Wales play their opening match against Uruguay on Sept. 20.
(Reporting by Martyn Herman,; Editing by Neville Dalton)