Former fly-half O’Gara, who was a two-time European champion with Munster Rugby and Sexton’s predecessor in the Ireland number 10 shirt, was particularly wary of the latter’s renewed threat with ball in hand.

He said: “Twelve months ago, Johnny wasn’t playing as good rugby as he is now. That's a positive for Leinster.

“First of all, he’s a great competitor and he loves rugby. People forget that.

“Rugby is such a great game, so you play it for as long as you can. He’s outstaying the rest in his position comfortably.

“I think he’s also been fuelled. There wasn’t much of a deal made of the fact that he didn’t make the Lions tour, but that would have hurt him deeply.

“That’s another example of his excellent resilience and his coming back.”

Sexton appears back to his best as he bids for a fifth European Cup winner’s medal.

O’Gara said: “I think he’s made changes to his game. He’s a very good passer of the ball, but he’s also becoming a threat again, which he may have put on the backburner for a number of months.

“You saw in the Toulouse game, his running game, his kicking game, his passing game.

“He’s very, very good at seeing the opportunity before other people see it. That’s what a lot of great 10s do.

“He sees things quicker than other people and he is able to manipulate his attackers and defenders into space because they have got great cohesion amongst them.”

Sexton didn’t play in last season’s semi-final defeat to La Rochelle, nor did scrum-half Jamison Gibson-Park, but O’Gara said his side must not place too much emphasis on the pair, despite their form.

He said: “They will have a different nine and a different 10 [from last year] and they’ll have a few changes up front as well, but I suppose their DNA stays the same.

“That's important when you’re trying to tell the French guys that they will be highly organised and highly skilled.

“We have got to take confidence from what happened last year. The key for us will be trying to start well.”

He added: “These are the games you want to be involved in and it’s fantastic for Stade Rochelais to be at this stage of the competition.”

The game in Marseille kicks off at 16:45 (UK & Irish time) and will be available to watch on BT Sport, Channel 4, Virgin Media, beIN SPORTS, France 2 and Sky Italia.

Stade Rochelais head coach Rona O’Gara praised Leinster Rugby fly-half Johnny Sexton’s resurgence ahead of Saturday’s Heineken Champions Cup final.