Jos Buttler has demanded England rediscover their "intensity" or face back-to-back Cricket World Cup defeats when they face Australia in their next game. Tournament hosts England crashed to a shock 20-run loss to Sri Lanka at Headingley on Friday. A heavily stacked batting line-up came undone in the face of a modest chase, bowled out for 212 as the underdogs landed an unexpected win. England have made a habit of reeling in far bigger totals in recent years and have already flexed their muscles with four scores more than 300 in the previous five games. The only time they did not reach that landmark was against the West Indies, when they romped to their target of 213 in less than 34 overs. The house came crashing down in Leeds, though, Joe Root's battling 57 and Ben Stokes' undefeated 82 the only real innings of substance in an unusually stodgy outing. "I think we lacked energy with the bat. I think we were a little bit passive as a group, which is what we haven't been for a long time with the bat," said Buttler, who made just 10 before becoming the last of four wickets for veteran paceman Lasith Malinga. "That is the most frustrating thing, to lose that intensity. That doesn't just mean hitting fours and sixes, that means showing intensity and trying to put pressure back on the bowlers. "It's more about strike rotation and showing that energy. As a mindset, we weren't at our best." Buttler understands that England will need to be right back up to speed for their next game, against rivals Australia at the home of cricket. Anything less would risk a third loss and leave the hosts vulnerable to an early exit. "That game will bring lots of intensity - England-Australia games are always big games and it's at a fantastic ground at Lord's," he said. "This result will hurt for a few days but we'll get ready for the next game." <strong>____________________</strong> <strong>____________________</strong> Whether dynamic opener Jason Roy is back to bolster the batting order remains to be seen. He has missed the last two fixtures with a torn hamstring and has yet to return to training. His deputy, James Vince, has proved a downgrade thus far and a return to fitness for the Surrey man is fast becoming a priority. "As a group we didn't have that intensity and obviously Jason is a guy who naturally does that," Buttler said. "But it's not just him, we can all do that from one to 11 so, as a side, that is the most disappointing thing - that we have played in a certain way for a long period of time and we went away from that."