Rob Howley has told Leigh Halfpenny and his fellow Cardiff Blues' Lions - Don't hold back against Leicester Tigers.
Halfpenny, Jamie Roberts and Andy Powell will tour with the British Lions for the first time while 2005 members Gethin Jenkins, Martyn Williams and Tom Shanklin also travel.
All six face a punishing end to the domestic season and before they become Lions, they must tame the Tigers in Sunday's Heineken Cup semi-final.
But Lions assistant coach Howley warned all 13 Welsh tourists not to live in fear of injury.
Howley said: "It's extremely difficult coming down from cloud nine after you've been named in the British Lions squad.
"There has been a lot of nervous emotion over the last few weeks as the announcement got closer. You've question yourself, your ability and whether you deserve to be selected.
"Now it has come, it's only natural to be desperate to stay injury free until you're on that plane.
"But the reality is, if you take your eye off the ball or you're not fully committed, that's when injuries happen.
"The focus has to be the semi-final of the Heineken Cup and for the others, finishing as strongly as possible in the league.
"Everyone selected has shown committment throughout the season and huge mental strength that will bare them in good stead for the next few weeks."
Howley, a European champion with Wasps in 2004, admits the Lions management are fearful of having 14 of the squad involved in a potential Blues-Munster Heineken Cup Final.
But the former scrum-half reckons it's a different story for the players after he admitted: "They wouldn't want anything different.
"Once you've reached the semi-final, you're one game away from a special occasion and with it the chance to do something amazing with your club.
"European cup finals don't come around every year, they're the pinnacle of six months hard work so every player must concentrate on that right now.
"As for the Lions coaches, this is the calendar we have to deal with. We're just praying they all come through unscathed."