England have been dealt yet another blow before their Six Nations title defence with Sam Underhill the latest frontline forward to withdraw from Eddie Jones’s squad on Tuesday. Underhill has a hip injury and after being assessed by England’s medical staff he pulled out with Wasps’ Jack Willis taking his place. Jones was already without Joe Marler, Mako Vunipola, Joe Launchbury and Kyle Sinckler for England’s Six Nations opener against Scotland on Saturday week and Underhill’s absence means he will be without half his first-choice pack. The Bath director of rugby, Stuart Hooper, is hopeful Underhill will be out of action for weeks rather than months, suggesting he may be fit before the end of the championship, but conceded England go into their Calcutta Cup clash without “one of the best flankers in the world”. “It is disappointing news first up for him,” said Hooper, who confirmed Underhill sustained the injury against Wasps this month. “The outlook is generally pretty positive. We are talking weeks rather than anything else. We know from Sam the destructive nature of his game and the ability he has got on both sides of the ball with carrying and defence.” Underhill’s injury means England’s formidable back-row trio, also featuring Billy Vunipola and Tom Curry, will be broken up for the foreseeable future with Willis, Ben Earl, Mark Wilson and Courtney Lawes among the options to step in. Wilson and Earl were included in the initial 28-man squad but the former has not played for England since last March and the latter has won all eight of his caps from the replacements bench. Lawes is fit again while Willis made a try-scoring debut against Georgia last November and has been promoted from the shadow squad. Jones, who will miss the first day of the training camp at St George’s Park on Wednesday because he is self-isolating, has also added Alec Hepburn – last seen in an England jersey in November – Dave Ribbans and Lewis Ludlam to those players effectively on standby. Meanwhile, Jones’s former assistant Paul Gustard has been appointed as Benetton’s defence coach, less than a week after his shock departure from Harlequins. Writing on his LinkedIn page, Gustard said: “I decided in December that I wanted a new experience and challenge, and was pleased to have so many different opportunities domestically, internationally and abroad available. I wanted to join a group where there was a clear vision, deep level of trust and a dynamic environment which was driven towards high performance.”