Six Nations 2018: England coach Eddie Jones wary of Finn Russell

Scotland fly-half Finn Russell is a "world-class" player who will have to be closely marked in Saturday's Calcutta Cup match at Murrayfield, says England boss Eddie Jones.

Two weeks ago, Jones baited Wales' Rhys Patchell, questioning his "bottle".

But the Australian has taken a different tack with Scotland kingpin Russell, who has struggled for form in the Six Nations so far.

"We will have to defend him very closely," Jones told BBC Sport.

"He went on a Lions tour and did some fantastic things in the French game. He's a world-class player."

Jones has also praised Scottish rugby, comparing it to the All Blacks both in terms of historical links and gameplan.

"Scottish rugby has always been closely aligned with New Zealand rugby," he said.

"The south island of New Zealand is very Scottish-based, and they played that fast-rucking game.

"Now their game is very similar to the All Blacks in the way they play, their kicking strategy is almost a carbon copy of the All Blacks' kicking strategy.

"And their attack in some ways is similar to the All Blacks attack.

"Gregor Townsend has probably liberated the team a little bit more than they were under [previous coach] Vern Cotter.

"Whether that's a good thing or not, we'll see."

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Fitter, tougher, happier

Ten of the starting XV from Eddie Jones' debut as England coach at Murrayfield are in the 2018 XV

Meanwhile, Jones says England have become a "fitter and mentally tougher" team since his first game in charge two years ago.

England ground out a 15-9 victory at Murrayfield in 2016, and have only lost once since, winning 24 out of 25 Test matches.

And Jones believes his side are much better prepared for the physical demands of Test rugby than they were under predecessor Stuart Lancaster.

"After the first training run - I had a look at it on video the other day - I was thinking: 'Goodness me what have I got myself into here?' The players weren't fit," he said.

"After 20 minutes, they were just shot. They couldn't run any more. The basics of Test rugby is physical conditioning. You've got to be fit enough to play.

"We've been looking at a bit of data and conservatively we've improved 40% - conservatively. And we've still got another 20% to go.

"I think we have also become a much more adaptable team. We've got a mindset of being able to grind out games if we need to, but at the same time if the opportunity allows we can move the ball well."

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Jones also says Murrayfield is one of the "most iconic grounds in world rugby" and his team have to prepare to face the whole of the Scottish nation.

"It's a small country batting above its weight, and I'm sure we will feel that on Saturday," he said.

"I spoke [to the players] about the honour of being able to play in the Calcutta Cup, it's one of the most historic games in the rugby calendar.

"They feel honoured to play in this game and I want them to be excited about playing in this game - but at the same time know they have a job to do."