Players not playing in the 2005 RBS 6 Nations Championship will have to have a "compelling reason" to force themselves into the reckoning for next June's British and Irish Lions' tour to New Zealand.
Speaking in Dublin, Lions coach Sir Clive Woodward once again distanced himself from the rumours linking former England internationals Martin Johnson, Neil Back and Lawrence Dallaglio with a Lions return in 2005 - stating: "I want to fundamentally pick players who are available for international rugby."
He added: "They don't have to be playing for their country. They may be back-up players who don't make the starting XV who still go on the Lions tour. The best example is '97 when Will Greenwood was uncapped.
"But I would never say never. I want to go with the strongest team, but that player really has to want to go on the Lions tour. Then we will consider him.
"I want players playing in the Six Nations to know they are playing for a Lions place and no one is going to come in from outside that selection criteria - unless there is a compelling reason to bring someone in."
The former England coach also refused to be drawn on naming the favourite for the captaincy role, revealing that it will be a collective decision.
He said: "It's a big decision and I want to be sitting down with Eddie (O'Sullivan) and Ian McGeechan and Andy Robinson to make sure we are all in agreement for who we choose."
However, without commenting on front-running duo Brian O'Driscoll and Jonny Wilkinson, he did highlight the leadership prospects of Ireland's Paul O'Connell, Scotland pair Gordon Bulloch and Simon Taylor, England winger Jason Robinson and new Welsh skipper Gareth Thomas.
"I've spend the last three or four weeks following New Zealand around Europe. I've been working with the Italian team, French team and Welsh team, seeing how they have been preparing," said Woodward.
"I think what has happened is my thoughts have been more crystallised about what the Lions is all about.
"More than ever I'm so pleased with the strength and unity of the four countries. It's critical we've got the four top coaches. Eddie (O'Sullivan) from Ireland obviously, Andy Robinson, Ian McGeechan from Scotland and Gareth Jenkins from Wales."
Although a budget has been set aside for 44 players to travel, Woodward did add that he may not bring that large a group.
Having studied previous Lions coach Graham Henry's All Blacks over the last fortnight, the former England coach feels under no illusions about how difficult a challenge lies ahead.
"Watching the New Zealand side against France the other weekend, more than ever we just have to be the best prepared team ever," Woodward said.
"I think everyone's feet are now firmly on the ground after we saw the way a full strength New Zealand team played against France. France prepared very well for that game."
Woodward, who will link up with each of the home nations during the Six Nations, will not
name a preliminary list of players. His final squad selection and choice for captain will be revealed on April 11 or 12.
England Under-18 head coach John Fletcher insists his young side will be better for the experience after beating Italy in the bronze final to round out their 2015 Rugby Europe U18 Championship campaign in style.