Earls' X factor marks him down as a huge threat
Keith Earls has revealed the secret to plucking crossfield kicks from the air at full tilt - 'X' marks the spot.
Ireland wing Earls will draw level on 65 caps with Shane Horgan and Simon Easterby in tomorrow's NatWest Six Nations clash with Wales in Dublin.
Even after a decade in Test rugby the 30-year-old appears quicker over the ground than ever.
The 2009 Lion says part of that sharpness is down to him marking an 'X' on the wall, sitting down and simply looking back and forth at that target.
Explaining his peripheral vision eye training, Earls said: "A lot of that is so that I can see the ball clearly while running at high speed.
"Claiming crossfield kicks is a massive part of the game for wingers, and thankfully some of that work has paid off in matches.
"It's as simple as putting an 'X' on a window or a wall, and moving your head back and forward, getting your eyes balanced with the gel in your ears so that when you're running at high speed you're not searching to see the ball.
"It can be quite hard to locate the ball clearly when running at speed, so I'm at an age now where every one per cent counts!"
A victory would inch Joe Schmidt's men one step closer to a likely tournament decider with England at Twickenham on March 17.
Earls clutched a crucial crossfield kick from Johnny Sexton in the build-up to the Lions fly-half's monster match-winning drop-goal in a stunning last-play move in Ireland's 15-13 win over France in Paris.
Sexton's drop-goal capped 41 phases of gritty Ireland build-up at the Stade de France, as the clock ticked towards 83 minutes.
Not only did Iain Henderson reclaim a 22 drop-out to set that multi-phase play off and running, but Earls also rose highest to Sexton's calculated gamble crossfield punt.
Earls admitted he has been working hard on the mechanics of fielding high balls in recent weeks.
"It would be something I'd do at home, or in the physio room at Munster, and sometimes people would wonder what the hell is this fella doing," said Earls.
"A couple of years ago I had a couple of bangs on the head which knocked my eyes out of sync with the gel in the ears.
"I went to the balance centre in Dublin and learned a few exercises. I've been doing them for a while, and I'm back into it again now."