David Cameron has flown back to Switzerland as England's bid to host the 2018 World Cup received a last-minute boost.
Mr Cameron's Russian counterpart Vladimir Putin confirmed he would not be travelling to Switzerland for Thursday's vote.
Prime Minister Putin also claimed Russia faced "unscrupulous competition", a remark which could be seen as criticism of the bidding process organised by football's world governing body Fifa.
The Russian bid and a joint one from Spain and Portugal are seen as England's main rivals.
However, the Candidatura Iberica bid also suffered a possible setback when it emerged that Portugal and Real Madrid star Cristiano Ronaldo would not be joining their delegation because of an ankle injury.
After a whistle-stop trip to Westminster, Mr Cameron got back on a plane to join Prince William and David Beckham ahead of the decision by Fifa's executive committee.
His spokesman told reporters: "The assessment at the present time is that it is going to go to the wire."
During Prime Minister's Questions, Mr Cameron said: "We have got the stadia, we have got the facilities, we have the transport networks, we have the enthusiasm in our country for football, and we can put on an absolutely first-class World Cup."
Prince William had breakfast with Fifa's Paraguayan member Nicolas Leoz as England looked to maintain momentum.
The meeting revealed England's determination to overcome any backlash from the Panorama row - Mr Leoz was one of three Fifa members accused by the BBC programme of taking bribes in the 1990s.