Number eight Billy Vunipola starts for the fourth successive match and captain Owen Farrell will play from the outset.

The match at St James' Park in Newcastle on Friday is England's last before they travel to Japan on Sunday.

"You can't worry about it and I'm not worried," said Watson, who makes his first start at full-back for England since an Achilles injury in March 2018.

"As soon as you start going into contact at 85% and start worrying about making sure you get on the plane on Sunday, you won't play as well as you can and you'd probably get injured anyway."

England open their World Cup campaign against Tonga on 22 September.

Wing Jack Nowell will still fly to Japan despite struggling with appendicitis and an ankle injury, while centres Henry Slade and Jonathan Joseph are still recovering from knee and leg muscle issues respectively.

One player who will not be risked on Friday is centre Manu Tuilagi, with Joe Marchant starting despite not being part of the World Cup squad.

Vunipola, who broke his arm three times in 2018, is the only player in head coach Eddie Jones' 31-man World Cup squad who will have started all four of the summer Tests, which could be considered a risk given Wales have already lost starting fly-half Gareth Anscombe to a warm-up injury.

But Farrell says 26-year-old forward Vunipola would not want to be sitting on the sidelines.

"Billy loves being out there, he loves being involved," he said. "He's looked in brilliant condition. He's been training well and playing well. It's good for him to get a run out."

England began their World Cup preparations with a convincing victory against Wales at Twickenham, before losing to the same opponents the following week. Jones' side recorded their biggest winning margin against Ireland then travelled to Treviso, Italy for a training camp.

Friday's match marks the first time an England Test will have been played at St James' Park.

Billy Vunipola has 44 England caps

Who will be England's World Cup full-back?

Elliot Daly had been Jones' first-choice full-back since last summer, but the 26-year-old has been rested for Italy's visit.

Watson, 25, is joined in the back three by Jonny May and Bath team-mate Ruaridh McConnochie, who is in the World Cup squad but has not yet won a cap because of injury.

After playing at wing for both of the matches against Wales, Watson insists he will not need a different approach for the change of position.

"My mindset doesn't really change that much. The roles of wing and full-back are very interchangeable," he explained.

"Playing wing in the last two games gives me a better perspective on what's expected from the full-back and what the full-back expects from his wingers.

"I just need to be very vocal, apart from that nothing really changes."

Wholesale changes for Italy

Italy coach Conor O'Shea has made 11 changes to the side that was beaten 47-19 by France last week, with captain Sergio Parisse rested for their final warm-up match.

New Zealand-born lock Dean Budd will lead the side and is joined in the pack by number eight Jimmy Tuivati, who is not in the World Cup squad.

Gloucester scrum-half Callum Braley, who captained England Under-20s to World Championship victory in 2014, makes his first start for Italy.

Italy begin their World Cup campaign against Namibia on 22 September.

Line-ups

England: Watson; McConnochie, Marchant, Francis, May; Farrell (c), Youngs; Marler, George, Cole, Launchbury, Lawes, Curry, Wilson, B Vunipola.

Replacements: Cowan-Dickie, Genge, Sinckler, Ewels, Kvesic, Heinz, Ford, Cokanasiga.

Italy: Hayward; Bellini, Bisegni, Benvenuti, Padovani; Canna, Braley; Quaglio, Fabiani, Ferrari, Sisi, Budd (c), Negri, Steyn,Tuivaiti.

Replacements: Zani, Lovotti, Riccioni, Ruzza, Zanni, Mbanda, Palazzani, Allan.