Warren Gatland is confident his Wales side will finish the job off.

• Gatland: ‘I pride myself on my record’
• Dispute with Ireland over Principality Stadium roof

A feature of Warren Gatland’s coaching career is that his teams tend to deliver when it matters. When he had a dig at England last month for bottling it on the big occasion, Wales’ coach did so from a position of having won six finals out of six with Wasps and Waikato and overseen two grand slams with Wales.

He also won and drew decisive Tests in charge of the Lions this decade and Gatland is drawing on his big-game experience as Wales aim for a third grand slam and fourth title in his final Six Nations with them by defeating the first country he coached, Ireland, in Cardiff on Saturday.

“I pride myself on the record I have had in big matches when it has really mattered,” Gatland said after announcing an unchanged 23. “I get even more of a buzz when people write us off, which has happened on a number of occasions. It’s about building belief and confidence in the players. It is important the coaches are positive and often it comes down to which team wants it that little bit more. If you want something badly enough and you really believe it can happen, it often does.”

A crucial match in Cardiff would not be complete without a dispute over whether the roof at the Principality Stadium should be open or closed. Wales prefer the latter, something Ireland agreed to two years ago only to find the sprinklers on shortly before kick-off.

Joe Schmidt said he was not prepared to leave the decision to Wales. “A lot was said two years ago about making it good for the spectators but the sprinklers were on for 30 minutes and the ground was very damp when the game started,” the Ireland coach said. “We might as well keep the roof open and let the rain come in rather than have it closed and wet.”

Wales have appealed to the Six Nations to make a ruling, with the weather forecast predicting heavy rain and strong winds. “It’s our stadium and we should be able to do what we want with it,” Gatland said.

Schmidt has made three changes to the Ireland side who defeated France on Sunday. The former Scarlet Tadhg Beirne and Sean O’Brien replace the injured Iain Henderson and Josh van der Flier, while Rob Kearney has recovered from a calf strain to return at full-back.

Wales are chasing a record fourth grand slam in the Six Nations era, with Gatland aiming to become the first coach to win three. One statistical quirk is they have only once this century defeated England and Ireland in Cardiff in the same championship campaign, 2005, and the previous year they managed it was in 1981.

“I have not seen a group as tight and close as this for a long time,” said Gatland, when asked to compare the squad with those in his grand slam years of 2008 and 2012. “Rob Evans [the prop] summed it up when he said there was not anyone in the squad he would not do something for or help out. Our message to the players this week has been that we will do whatever it takes to get them prepared and we have had a couple of unusual requests.”

Gatland knows Ireland will not surrender their title, or second place in the world rankings, without giving everything. Discipline will be key for Wales if they are to keep the ball in play and deny their opponents penalties to kick to touch and drive lineouts, the source of three of their four tries against France. Wales were penalised only three times against England, a figure that rose to 11 in Scotland.

“I have already spoken to the referee [Angus Gardner],” Gatland said. “Our discipline against England was such we negated their set piece: they would have spent three or four hours working on lineouts and it was a waste of time as they had only four. We must not allow Ireland a platform to work off, and a big part of that is making sure our discipline is good. I told the referee we were not at our best last week with some of the penalties we conceded and it has been a big focus for us this week.”

Like Gatland, Schmidt is preparing his side for the final time in the Six Nations. “It has been a frustrating tournament for us,” he said. “We started on a really flat note against England and have not been as cohesive as we would have liked but we go into the final weekend still in contention for the title.”