Injury-hit England had to settle for a 1-1 draw with World Cup co-hosts South Korea in a pre-tournament friendly on Tuesday.
Captain Michael Owen scored in a 25th-minute goalmouth melee, but after manager Sven-Goran Eriksson made seven halftime changes his team were pegged back by Park Ji-Sung's 52nd minute header.
England, playing an unfamiliar 4-3-3 formation and with four players out through injury, had the mobile South Koreans under control in the first half.
But the wholesale substitutions tore all shape from their game in the second and they had to withstand a late charge from the hosts on Cheju island.
"I know that we can play better but it's in 12-13 days (time) that we need to play very good football," said Eriksson, whose team open their group F campaign against Sweden in Japan on June 2.
"In the first half we did rather a good job but second half we complicated life a little bit. But that's okay, we've only been here for a couple of days," Eriksson told Sky Sports television.
"Korea were a very aggressive team, very good on the ball and I think they could cause a small surprise in the tournament. They play good football."
Eriksson, who must submit his final 23-man squad list to world body FIFA by the deadline of midnight Zurich time on Tuesday, said he had picked up no new injury worries, although midfielder Owen Hargreaves had "a slight knock" to his knee.
"I don't think it's anything serious at all," Eriksson said.
England's first real chance came after 14 minutes when Hargreaves, impressive in central midfield, sent a long ball forward for Owen. The skipper's flick wide of the keeper found Darius Vassell, but the Aston Villa striker's effort under pressure was cleared off the line by Choi Jin-Cheul.
The breakthrough came after Owen started a three-man move on the edge of the area, with Emile Heskey picking out Paul Scholes for a shot which the keeper parried -- only for the Liverpool striker to bundle the ball home.
Owen had also opened the scoring in his previous match as stand-in captain for the injured David Beckham, last month's 4-0 friendly win over Paraguay at Anfield. Tuesday's strike took his career tally for England to 15 goals in 34 games.
Unable to make much impression on England's rearguard, South Korea resorted to shooting from outside the area.
Though Lee Chun-Soo and Lee Young-pyo both ballooned their efforts, a stunning 30-metre drive from skipper Hong Myung-bo forced Nigel Martyn into his first real save of the match.
The hosts kept pushing for an equaliser, but were not rewarded until just after the break when Lee Chun-Soo's corner was headed on and Park, left completely unmarked in the six-yard box, nodded past David James.
The absence from the finals of injured England right-back Gary Neville was keenly felt, as Danny Mills struggled to contain Lee Chun-Soo before making way for Wes Brown in the 67th minute.
England gradually recovered their poise but despite the promising efforts of substitute Joe Cole they lacked any real bite in attack.
Owen said he was impressed by the Koreans.
"People have underestimated the Asian teams and the African teams for a long time but we knew they were a good side and they proved they can play a bit.
"That was just feeling our way in feeling the climate and the different conditions we are going to expect.
"The main thing today was to have a game, a run-out and obviously no injuries. We've got another game under our belts together and we're going to improve from that now."
Eriksson was due to name his final World Cup squad a few hours after the game -- choosing between Kieron Dyer, who is recovering from a knee injury, and standby Trevor Sinclair, a second-half substitute on Tuesday.
England play Cameroon in their final pre-tournament friendly on May 26 at Kobe, Japan.