Joe McCarthy has given Andy Farrell his biggest headache ahead of Ireland's Six Nations opener with France, according to The Irish Times' Gerry Thornley.
Ireland open their Grand Slam defence with a mouth-watering encounter against France in Marseille on the first Friday of February.
It will be the first game for Andy Farrell's men since their agonising quarter-final exit in last year's World Cup, and the first in a new era without Johnny Sexton as Ireland captain.
The challenge does not get tougher for Ireland than France though, as France too are coming off the back of the narrowest of defeats at their home World Cup at the same quarter final stage.
With Sexton and Keith Earls both retiring, as well as a number of injuries across the park, one area that Ireland would have felt comfortable in going into the Championship was at lock, with James Ryan, Tadhg Beirne and Iain Henderson all locked into their respective roles in recent years. Enter one Joe McCarthy to throw a spanner in the works.
McCarthy has a touch of Etzebeth about him
Speaking on Wednesday Night Rugby, rugby correspondent with The Irish Times Gerry Thornley looked back on Leinster's Champions Cup victory over Leicester Tigers, and one outstanding performance from the young second row.
"The performance of Joe McCarthy [was very striking]," Thornley said. "There was one break down the left wing, I think it was by [James] Lowe, he was the first forward on the scene.
"They were comparing him on commentary to [Eben] Etzebeth. There's a little bit of Etzebeth, alright, in him. He's got that narkiness in him, he's spoiling for a scrap.
"But he's very mobile. I know he's young, so he should be, but he's got good footwork. I think it's making the second row the single most difficult position for Andy Farrell to pick against France."
Just the presence of a man the size and dimensions of McCarthy in an Ireland camp is an anomaly in itself. Thornley feels that the match up with France is the ideal time to start the massive Leinster forward.
"There's a strong argument now, the wrecking ball impact he would be off the bench, there's an argument to start him as well," Thornley said.
"Big locks like Joe McCarthy, Will Skelton, Emmanuel Meafou, they're thin enough on the ground. For Ireland to have one for, perhaps, the first time in history is quite remarkable. This guy really is an exceptional beast."s
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