Ellen White scored twice as they got their campaign off to a perfect start with a 2-0 win over Chile in Sapporo on Wednesday.
Williams, who was part of the GB side which reached the quarter-finals at London 2012, says expectations should be much higher this time.
“For the women’s game the Olympics is equally important as the Euros and World Cup,” Williams, who is playing at Soccer Aid for UNICEF, told the PA news agency.
“In the men’s game it’s a bit different; the World Cup is the pinnacle. But the women are out there to get gold and they’ve got a chance.
“The expectation has to be higher. Our game has now been full-time professional for a number of years here.
“The English players have developed tactically and technically, and the fitness levels – in 2012 we were part time and the players probably weren’t fit enough at the highest level.
“There’s every reason that we should be thought of as a team who should be winning a medal at the tournament.
“With all the funding that has gone in behind the scenes as an England team – and I know we have a couple of Scotland and Wales internationals but they play in the WSL, so in terms of funding they’ve had that – there’s an expectation, and rightly so, with what’s gone before especially as an England team. So they are expected to medal.”
Nine of the team which started against Chile were English – with a sprinkling of Scotland in midfield – making Tokyo a useful exercise in terms of preparation for next year’s home European Championships.
“What this England team miss is what they have now in the GB team, the impact that Caroline Weir and Kim Little have in that midfield in terms of dominating,” added Williams.
“I think that’s what England lack a little bit, so that’s why this GB team is exciting. But if they can get gold and silver that’s important for the mindset going into next year’s home Euros when the expectation will be even higher.”
Williams, capped 170 times by England, hung up her boots at the end of the season but is making a comeback of sorts by playing at Soccer Aid for UNICEF in September.
The former midfielder will line up at the Etihad Stadium alongside the likes of Wayne Rooney, Paul Scholes and Ashley Cole against a World XI which will not be found wanting for pace.
“It’s my first time and I’m looking forward to it,” added Williams. “But I might ask if I can ask to play a bit higher up the pitch, furthest away from Usain Bolt!
“I’m excited to play alongside my old team-mate Kelly Smith again and the likes of Rooney, Scholes, players I’ve admired for years. To be able to put my feet on the pitch with them is very exciting.”
:: Soccer Aid for UNICEF 2021 takes place on Saturday September 4th at the Etihad Stadium. The money raised from this year’s game will help UNICEF fight back against the Covid-19 pandemic by helping to deliver two billion vaccines worldwide. Tickets are available at: www.socceraid.org.uk/tickets ::