England's coaches struggling for answers after Fiji loss as World Cup looms
England lost for the first time ever to Fiji when they went down 22-30 in a warm-up at their Twickenham home on Saturday
Opening Pool D opponents Argentina and Japan will have every confidence they can upset the 2019 finalists, with England's defence in particular leaking an average of around four tries per game across the summer series of warm-up fixtures.
"We slipped off too many tackles and whilst that has not been the case in previous games it was today and it's an area we clearly need to get right in two weeks' time," Borthwick said looking ahead to next month's tournament in France.
However, England's woes are many.
Talisman Owen Farrell is suspended for the potentially decisive opening two games after a red card in the warm-ups, while their only specialist number eight Billy Vunipola is also ruled out after a red in the defeat by Ireland.
Joe Marler escaped a card for an upright-looking tackle on Saturday, with Borthwick saying he had no view on whether the prop could face disciplinary action if the incident is reviewed.
"I'm very happy with this squad of players," he said, adding that where previous England squads had succumbed to in-fighting when results turned, this group were pulling together.
But Borthwick had no update on England's lengthy injury list, with the squad to be finalised on Saturday evening.
Combative flanker Tom Curry and prop Kyle Sinckler are among the injured, as are wingers Elliot Daly and Henry Arundell, with England already having ruled out scrum half Jack van Poortvliet and winger Anthony Watson for the tournament.
Courtney Lawes on the occasion of his 100th cap for England had few answers for reporters on how England might improve before their game against Argentina on September 9.
"It's pretty disappointing... We're not going to give up," he said.
Quicksilver young fly half Marcus Smith, who has lately lost his starting place, offered one of the few positives on Saturday with a try that may strengthen calls for him to be reinstated in a bid to revive England's moribund attack.
"I thought Marcus came on and played very well and gave us that bit more on the edges," Borthwick said. "He is a real threat and we saw that same threat last week as well."