ROME (AP) — England successfully began its bid for a record third straight outright Six Nations title with seven tries but it could be left counting the cost of Sunday's 46-15 win in Italy after injury to Ben Youngs.

Youngs was carted off on a stretcher less than 10 minutes into his 56th start for England, which overtook Matt Dawson's record of most starts for an England scrum-half.

England was already 5-0 up by then and Anthony Watson scored his second try of the day as the golf cart carrying Youngs was still circulating the pitch.

Six Nations debutant Sam Simmonds also scored two tries, in the second half, while George Ford and Jack Nowell turned over for England late on as Italy collapsed.

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Owen Farrell missed the first two conversions but he racked up England's third try and added the extras on that occasion as well as on his next three attempts.

Tommaso Benvenuti and Mattia Bellini turned over for Italy, both following wonderful passes from Tommaso Allan, who converted one and scored a penalty kick.

England moved to the top of the table, ahead of Wales on goal difference.

Italy had lost its past 12 Six Nations matches and all 23 of its previous matches against England.

In this fixture last year, Italy used a tactic dubbed "The Fox" at Twickenham to bamboozle England by frequently not contesting the breakdown.

There was to be no repeat this time around and England raced into an early lead as some slick passing following a lineout on the left deep in Italy's 22 saw the ball reach Watson, who turned over in the far corner.

Farrell's kick rebounded off the right post.

Shortly after, Youngs went down with what looked like a nasty knee injury after his left leg appeared to get trapped in the ruck. The Leicester scrum-half had several minutes of treatment on the pitch before being taken off on a stretcher on a golf cart to applause from more than 61,000 fans at the Stadio Olimpico.

He was replaced by Danny Care, who became England's joint most-capped scrum half with Dawson on 77 caps.

England extended its advantage moments after play resumed as the ball was once again played through hands with lightning speed and Watson raced down the right flank to again turn over in the corner, just as the cart carrying Youngs was passing.

Farrell again missed, this time sending his kick wide of the left.

The Azzurri managed to reduce the deficit midway through the half.

Following a good counterattack, Tommaso Boni was brought down on the left, near the five-meter line, but Italy managed to recycle the ball and a delightful looping long pass from Allan sucked in Jonny May and sent Benvenuti clear to score in the right corner.

Allan added the extras and the gap was down to just three points.

However, Italy's fragile defense was again exposed after sustained pressure from England inside the 22, and Farrell gathered a pass to run through a gaping hole and turn over.

Farrell converted what was only his sixth try in 54 matches for England.

Italy piled on the pressure at the end of the half but, after several phases near the five-meter line, it had to content itself with an Allan penalty kick to leave it 17-10 at the break.

Watson fumbled over between the posts at the start of the second half but it was ruled out as Care's pass was forward.

England inched 10 points clear with a penalty from Farrell before Italy had a try ruled out after consultation with the TMO as Allan's pass to send Boni through was forward.

Simmonds had been one of England's hardest workers, with 16 tackles inside the first 50 minutes, and he scored on his Six Nations debut, rushing forward unchallenged following a quick maul from a lineout.

Italy refused to let England get away, however, and Bellini touched down in the left corner in the 58th minute following another wonderful pass from Allan.

However, that was to prove a false dawn and, with the Azzurri looking ragged, England took full advantage, turning over three times in the final 12 minutes.