Rob Kearney has thanked the British and Irish Lions coaching staff for sticking with him during his fightback from injury.

Ireland full-back Kearney is set to make a belated first tour appearance after being named among the replacements for tomorrow's appointment with New South Wales Waratahs.

But he might not even have set foot in Australia had his torn hamstring been a more serious problem than it transpired.

"If there is one time in four years not to pick up an injury or little niggle it is at the start of a Lions tour," Kearney said today.

"My timing couldn't have been any worse.

"I got a scan done in Hong Kong, and it could easily have gone either way. I could have been getting the first flight back to Dublin, or going off to Australia with the lads.

"It does give you a bit of perspective, especially when you then see a few boys heading home like Cian (Healy) and Gethin (Jenkins). Then you start to feel that luck is on your side.

"Then you get the chance this weekend to put the jersey on again, which is a fantastic feeling, albeit it might be a little bit late."

Kearney, 27, replaced an injured Lee Byrne during the first Lions Test in South Africa four years ago, and he went on to become a pivotal player for the tourists during that series.

This time around, he has significant ground to make up on the anticipated first Test Lions number 15 Leigh Halfpenny, but Kearney insists it will not be for the lack of trying.

"Leigh has done fantastically well," he added.

"He found himself in the (Wales) full-back position by chance a little bit. James Hook was there for a while, and after Lee Byrne they never really had an established full-back, and he stepped in there and made the position his own pretty quickly.

"I think he has gone from strength to strength. I would like to think I can push him.

"The timing hasn't been great, and his 11 from 11 (successful goal-kicks against Western Force) hasn't helped me, but there is a lot to happen on this tour.

"If there is one time in four years not to pick up an injury or little niggle it is at the start of a Lions tour" - Rob Kearney.

"Not just in rugby, but in sport in general, things can happen in a matter of seconds and things can take a U-turn pretty quickly. It is firmly in my mind that there is still a challenge there.

"Being in that scanning machine was a low point because I had no idea what the results were going to read.

"I was pretty chuffed with the coaching staff when they gave me the chance to hang on for two weeks without any involvement. I took a bit of confidence from that.

"The lads think I've been on a three-week holiday. I can't give them too much stick back because I've just had to put my head down and take it."

While Kearney prepares for a 2013 Lions tour bow, his Ireland team-mate Simon Zebo will make a debut in the famous red shirt. This time last week, he was preparing to face the US Eagles in Texas.

The 23-year-old arrived in Australia on Tuesday after being summoned as cover for hand injury victim Tommy Bowe, and he has made tomorrow's starting XV, wearing the number 11 shirt.

With George North reporting a tight hamstring against the Combined Country XV three days ago and not training today, Munster back Zebo could even thrust himself into the Test picture if he shines tomorrow.

"It has been nothing but excitement ever since I got out here. I am happy to be here," said Zebo, who had an ice pack strapped to his thigh today, but dismissed any fears about his fitness.

"I think it was three flights I took in total, with a few fuel stops and a few delays. I had a bit of work catching up on my sleep, but I am nearly there now.

"It's an opportunity for all 23 players involved tomorrow. Any time you get to go out and wear that special red jersey it's an honour and a great opportunity.

"These Test series don't come around too often, so any chance you get to represent the Lions you are going to do it with pride and hopefully put your best foot forward for those Test games. That is something we will be looking to do tomorrow night."