Andy Farrell guarantees Johnny Sexton will be fit and ready for trip to Paris

Andy Farrell has allayed any concerns that Johnny Sexton might miss Ireland’s pivotal match against France in Dublin next weekend. Ireland’s captain was nursing a dead leg after a collision with Liam Williams, for which the Wales full-back was shown a yellow card, but the injury is not serious.

Williams went to the sin-bin for making contact with Sexton’s head. When the latter received treatment after the collision, the referee insisted he leave for a head injury assessment. Sexton protested that he was being treated for a leg injury. He consequently passed the HIA.

Related: Borthwick admits England face ‘big challenge’ after letting Scotland lead slip

Sexton was playing for the first time since New Year’s Day, when he sustained a cheekbone injury that required surgery. The 37-year-old seemed to return with ease, scoring 12 points against Wales with five kicks from five. Farrell hailed his character and rejected any suggestion he might be getting too old for all this.

“There are no doubts about his age in our mind,” he said. “I spoke to him constantly over the last two weeks. I told him there’s no excuses. He said he’d never been so nervous before a game. How he handles that and runs the team, making it feel right, and then goes out and performs at the same time is testament to his character.”

There will be no room for doubts in Dublin next weekend. Ireland have lost their past three matches against France, who rushed off to an early lead in Paris last year. “Not being ourselves was the main thing,” Farrell said. “We didn’t attack the game how we can do in the first 15, 20 minutes. We got ourselves back into the game and had a chance of winning. So being ourselves from the start would help.”

Ireland showed themselves how in Cardiff. They burst into a 14-0 lead in the first 10 minutes with tries from Caelan Doris and James Ryan, before James Lowe intercepted on his own 22 to score a third at the end of the first quarter. Ireland led 27-3 at the break.

Related: Six Nations can help lift rugby’s gloom and show what the game can really be | Ugo Monye

Some sort of response from Wales was inevitable. They replied with a slick try from Williams a few minutes into the second half but never looked likely to threaten Ireland’s lead. When Williams was in the sin-bin, Ireland raised their game again to score a bonus-point try through Josh van der Flier in the last 10 minutes.

They are looking regal at the top of the world rankings, but Farrell is braced for the arrival of France. “I think everyone realises what’s coming next week, but there’s one thing about an Irish crowd. When there’s a big game and they know they have to get behind the team, they are the best in the world. There’s no doubt about that.”

The best crowd in the world cheering on the best team. The stage is set.