Warren Gatland's Wales have been badly hit by injury - but captain Alun Wyn Jones is fit to lead from the front

Wales head coach Warren Gatland has warned that the step up between club and international rugby is "absolutely huge", as he prepares to pick a side laden with Scarlets players.

There could be as many as 11 from the Scarlets in the Wales XV for the Six Nations opener against Scotland.

But Gatland says the Test arena is a different beast to the club game.

"The step up is absolutely massive - people don't understand that," Gatland told the Rugby Union Weekly podcast.

"The best example we have of that was in the autumn, with [debutant centre] Hadleigh Parkes.

"He came off that field and said 'oh my God, I cannot believe the step up from what I've ever done before to playing international rugby against South Africa'.

"As a coach I have to keep reminding myself about the pressure and intensity the players experience when they step on that field at international level."

Injuries this week to the Ospreys pair of Rhys Webb and Dan Biggar, as well as Saracens back Liam Williams, have opened the door for the likes of Scarlets trio Gareth Davies, Rhys Patchell and Leigh Halfpenny.

The Scarlets - who won the last ever edition of the Pro12 last season before it became the Pro14 - have been one of the standout sides in Europe this season, reaching the Champions Cup quarter-finals, but Gatland says it's not as simple as taking their template into the international arena.

"It's just a reminder to people that, yes we watch club rugby and [take] certain things, but that step up is absolutely huge," he said.

Longevity hard for coaches in modern game

Meanwhile, Gatland says the hiring and firing culture creeping into rugby union will make it difficult for coaches to have an extended stay in one job.

The upcoming Six Nations marks a decade in the role for Gatland, who took charge of his first Championship as Wales head coach in 2008.

"There was no way I thought I would be here for 10 years," Gatland said.

Warren Gatland first took charge of Wales back in 2008

"It's hard for coaches to stay in jobs for an extended period."

Gatland was speaking in the week that the Ospreys head coach Steve Tandy lost his job, while Northampton have dispensed with the services of Jim Mallinder already this season.

"You look at football, and longevity in rugby is going a little bit the same way now," he said.

During his tenure, Gatland has twice been given time off by Wales to coach the British and Irish Lions - most recently against the All Blacks last summer - and he feels these spells have contributed to his longevity.

"The lucky thing is I've had two sabbaticals - 2013 and 2017 away with the Lions - and time away re-energises you and keeps you coming back with fresh ideas, being involved with different coaches and different players," he said.

"This is maybe why I've lasted a little bit longer than normal."

The early years of Gatland's tenure coincided with a period of domination for Wales, with Grand Slams in 2008 and 2012.

However, with no title since 2013, Wales find themselves considerable outsiders for this year's Championship, a source of inspiration for Gatland.

"That drives you on. I don't know whether that's me as a competitor, but as a coach I hate losing," he added.

"I can accept it, but it spurs you on and you learn the most from your defeats and disappointment.

"The fact there isn't any expectation on us I think is a nice position to be in. So if you are getting 15 or 16-1 for the Six Nations, run out to the bookies and go and get your money on us."