Ross Byrne is a rugby enigma. When he replaces Johnny Sexton for European heavyweights Leinster he is sublime but he is struggling to make his mark for Ireland.
Leinster coaching duo Leo Cullen and Stuart Lancaster had enough confidence in the 26-year-old to give him the nod ahead of Sexton in the Pro14 final victory over Munster in March.
That means there will no alarm bells as the fly-half pulls the strings from the start in Sunday's Champions Cup semi-final against French side La Rochelle.
Byrne's assured performance when he came on after Sexton suffered a head knock in Leinster's quarter-final win over reigning champions Exeter confirmed he can deal with pressure at the sharp end of club rugby.
"With regards to Ross driving the team when he came on, I thought he was excellent against the Chiefs," Leinster's assistant coach Robin McBryde said this week.
"He's probably got a little bit more tempo in his game than Johnny, to be fair.
"I've been very impressed with the relationship between him and the lineout caller and the speed they're able to work together. The lines of communication are just so quick."
Byrne, who will be making his 100th appearance for the four-time European champions, has been a lucky talisman for the team, who have won all 11 matches in European competition in which he has started.
In 23 European appearances in all he has ended up on the losing side just once -- last season's quarter-final against Saracens.
It is no wonder Byrne has been touted as a potential long-term successor for Sexton at Test level but he faces a battle to convince Ireland head coach Andy Farrell that he is the man for the job.
- 'Kick on now' -
Ulster's Billy Burns has been preferred recently as the stand-in for Sexton, who turns 36 in July.
Farrell admires the "dynamism" of Burns and picked him to start against France in their Six Nations match in February when Sexton was out with another head knock.
Former Ireland international Alan Quinlan said Byrne -- capped 13 times but with just two starts under his belt -- is not the first player to find it difficult to bridge the gap between club and country.
"Byrne did (play very well for Leinster against Exeter) but he has got to do it for Ireland," Quinlan told the Off The Ball sports show in April.
"That is how he stops that talk (about his difficulties at international level) you know. I think he has shown on numerous occasions that he is talented enough.
"Byrne has the quality but there is a difference (between club and international rugby) with respect to anyone that would make the argument that he should be starting for Ireland when Sexton is not there."
Quinlan said one issue for Byrne was the challenge of adapting to different playing styles.
"Leinster play a lot differently," said Quinlan. "The way Leinster play seems to give Byrne a lot of confidence and belief.
"Byrne may not get the same space and time at international level. "Can he do it? Of course he can but he has got to kick on now and really believe in himself."