An own goal after four minutes from Paraguay captain Carlos Gamarra handed England a 1-0 win that was anything but the convincing display England boss Sven-Göran Eriksson had been seeking from his super-confident squad.
"We can play much better but I am happy today - it's three points," Eriksson said. "The most important thing was to get three points and we got them. So It's a good start."
England captain David Beckham said the 30-degree heat at a sweltering Waldstadion had taken its toll but admitted his side had committed far too many basic errors for comfort.
"We were good at times but we give ball away too much. We got what we wanted. The performance can be better and we've got to work on that," adding he was not discouraged that England had made such hard work of their opponents.
"We would have liked to have played better but on the other hand I think it's the mark of a strong team that we can not play at our best and still get a result," he said.
Paraguay coach Anibal Ruiz said he believed the South Americans had outplayed their star-studded opponents for much of the second half.
"We were playing a very strong team with very strong players but I felt that we managed to control them. For a lot of the time we were superior," Ruiz said, acknowledging that the heat had been a factor.
"In the second half I think we dealt with the heat better than them because we are used to it. That's why we were stronger physically," he said.
Prince William, the second-in-line to the British throne, was among an estimated 35,000 England fans crammed into the ground. But Beckham and co conspicuously failed to lay on an attacking feast fit for a future king, with strikers Peter Crouch and Michael Owen both struggling to get on target.
England's problems in front of goal were summed up by the telling statistic that they failed to have a single shot from inside the area.
Nevertheless Eriksson remains confident that his side can emerge as genuine title contenders.
"To win the World Cup we will have to play better football, and I know we can play better football," said Eriksson.
The Swede did at least take away the satisfaction of having improved England's dismal record of winning only one opening match of a major tournament in the past 20 years, knowing that a victory over minnows Trinidad and Tobago in Nuremberg next Thursday will put them into the next round.
Yet the return to match fitness of Manchester United star Wayne Rooney clearly cannot come soon enough for England, who failed to build on the dream start handed to them by Gamarra's own goal.
Once again the goal came via Beckham's right boot, the Real Madrid star sending a wicked inswinging free-kick into the box that Gamarra glanced past goalkeeper Justo Villar.
A disastrous opening for Paraguay got worse only a few minutes later when Villar limped off with what looked like an injury to his right leg.
England, with Steven Gerrard outstanding in central midfield after recovering from a pre-match injury scare, threatened to run riot early on against a Paraguayan side that seemed paralysed by nerves.
Gerrard saw an ambitious volley fly over the bar on 10 minutes and seconds later produced a sublime pass that sent former Owen bearing down on goal.
Owen, who has hardly played this year after breaking his foot last December, was let down by his first touch however, allowing Paraguay to clear the danger. It was typical of what would prove to be an unhappy afternoon for Owen, who was replaced by Stewart Downing on 53 minutes.
Paraguay had to wait until the 18th minute before their first meaningful chance, when a rare foray into England territory ended with Carlos Paredes shooting wide.
There was bad news for England when Gerrard was booked by fussy Mexican referee Marco Rodriguez after a challenge on Cristian Riveros that appeared to make minimal contact.
Paraguay's best chance came in the closing minutes of the half when Werder Bremen's Nelson Valdez lashed a shot just wide of the right-hand post as Paraguay capitalised on a slip by England left-back Ashley Cole.
England again started brightly in the second half, with Chelsea midfielder Joe Cole impressing after being shifted into the hole behind Crouch after Owen's substitution.
But an increasingly confident Paraguay had alarm bells ringing in the England defence on 60 minutes when keeper Paul Robinson could only palm a Carlos Bonet cross to Paredes, who hooked his volley over.
A yellow card for Crouch on 63 minutes summed up England's frustration as both sides tired.
Frank Lampard looked the most likely to increase England's goal tally, twice seeing long-range shots well-save by Paraguay replacement keeper Aldo Bobadilla.