London - Excitement will be mixed with concern when four of Europe's leading rugby nations begin their World Cup warm-up programme this weekend.
Ireland play Italy in Dublin on Saturday, with England facing Wales at Twickenham a day later.
While some players can be reasonably certain of being on the plane to Japan, for others the next few weeks represent a last chance to impress.
Not that England have that long with their Australian coach Eddie Jones -- brought in after the team's first-round exit on home soil at the 2015 edition -- naming his World Cup squad on Monday.
But John Mitchell, England's assistant coach, said Friday: "I don't see it as a one chance.
"Every day in our environment is selection and observation; it doesn't just come down to one game. Every day we are looking at what they do, how they do it, how they adapt, how they cope with pressure, how they relax, how they connect."
Nevertheless Mitchell, head coach of his native New Zealand when they reached the semi-finals of the 2003 World Cup in Australia won by England, was well aware of what was at stake.
"It's a difficult time for a head coach -- you are making big decisions on young men's careers," he said.
"They all want to go to a World Cup. Having been in those shoes before, I can fully empathise with the feelings and emotions that he (Jones) goes through. But it is the head coach's responsibility."
England have picked an experimental side, leaving out several first-choice players and giving debuts to Bath wing Ruaridh McConnochie and Gloucester scrum-half Willi Heinz.
Ireland, meanwhile have selected a South African-born lock in Jean Kleyn, who only became eligible under residency rules earlier this week.
Grand Slam champions Wales, however, have selected something close to their strongest side.
Mitchell, asked whether England's priority on Sunday was to win or learn something about players that could only be discovered under match conditions, replied: "If you get both, that's good."
Sunday's match will be the first of two back-to-back fixtures between England and Wales.
Both sides are playing four warm-ups in total, with Wales also involved in a double-header with Ireland.
Commercial considerations are clearly a factor, with unions looking to make-up for the loss of income they would otherwise suffer in a World Cup year without any November internationals
But such a programme has raised fears that, in an ever more brutal sport, players could suffer injuries that rule them out of the World Cup before the tournament starts.
This has happened before but Wales great JPR Williams -- who away from rugby was a surgeon -- has condemned the current schedule as "ridiculous".
"Both England and Ireland can put two sides out on the park while we'll have to risk some of our more senior players," he told the Rugby Paper.
"It would be awful if we lost some of our best players on the eve of the World Cup."
Wales could knock New Zealand off the top of the world rankings this weekend if they beat England and other results go their way.
But Wales coach Warren Gatland, who played in the same Waikato side as Mitchell, accepted Williams's point.
"The criticism is fair," he said. "You can't get it right all the time. You are trying to negotiate warm-up games with sides and trying to get the balance right.
"It's a little bit of a concern that you don't pick up too many injuries, but sometimes you have just got to roll the dice and go with it."