Coach Hope Powell says England are not taking a win for granted ahead of their World Cup opener against Mexico.
Powell's team are looking to better their quarter-final appearances of 1995 in Sweden and 2007 in China.
She will want England to top Group B to avoid a likely last-eight meeting with world and European champions Germany.
Mexico have recently beaten the United States - the world's top-ranked team - and Powell said ahead of Monday's game: "Technically they are very good."
She added: "Forward Maribel Dominguez is a world-class player, but if we just focus on her we'll be in trouble."
England face New Zealand and Japan in their other group games, with all their matches being shown live on the BBC.
Powell has said the 21-player England squad is the strongest group she has taken to a major championship in the 13 years she has been in charge.
But although captain Faye White and star midfielder Fara Williams have overcome knee injuries, preparations have not been helped by training-game defeats by North Korea and Australia in the past week.
The two losses, in which England failed to score, added to their coach's concerns that some of her players may not be sharp enough.
All but five of them compete in the newly-formed Women's Super League in England and have only played seven league games in the build-up to the tournament in Germany.
Powell played down the 3-0 defeat by North Korea and the 2-0 loss to Australia, saying: "We've done well in training games before and in the last two we haven't done so well.
"Obviously we need to address that, certainly for Monday, but it is when points are at stake that you want the performance."
England, who are 10th in Fifa's rankings, have recently beaten two-time World Cup winners the United States, and the world's fifth-ranked team Sweden.
They also qualified for the tournament unbeaten and reached the European Championship final two years ago, where they were thrashed 6-2 by Germany.
Though Mexico are ranked 22nd in the world, they too have beaten the US in qualifying for the World Cup and the Swedes in a friendly.
White, who says she will relish what could be her last World Cup, also believes England cannot underestimate their opponents at the Wolfsburg Arena.
She regards Mexico as being representative of the improvement in the international women's game, as shown by hosts Germany's narrow 2-1 victory over Canada in their opening match of the World Cup.
"Every team that gets to a World Cup has to have a good pedigree," White told BBC Sport.
"Not only have we progressed and developed, so have other nations and the gap between the top five or six teams and the rest is narrowing.
"Mexico had a great closed-game result against Sweden last week so I don't think you can underestimate them. In the 2007 World Cup we had a game against Argentina which we won 6-1, but I would be surprised if we saw a score like that in this World Cup."
England's star forward Kelly Smith is expected play a big part in any success in Germany.
The 32-year-old scored four times at the 2007 World Cup and White thinks the team can now give her the support to make an even bigger impact on the world's biggest stage.
"Kelly has been one of the top three players in the world over the last few seasons and that's as England have improved as a team as well," White added. "Players like Marta from Brazil or Birgit Prinz from Germany, they have been up there for a few years too.
"Kelly has always had that ability but you need [to be in] a team which is playing at the top level, competing against the best teams to help her.
"She brings something special to this team without question. She has shown in the last few tournaments what she can do and I certainly hope, as her room-mate, that she can deliver and that this one is special for her and the team as well.
"China was a fantastic experience for me personally but also the other girls and I believe this is going to be even better."