Cardiff: Wales produced a defensive effort for the ages to beat Ireland 23-16 in a heart-stopper and stay afloat in the Six Nations, while ruining the visitors’ Grand Slam hopes at Millennium Stadium on Saturday.

Ireland, bidding for only their third ever clean sweep, can still win successive championships for the first time since 1949 when they go to Scotland next week, but it will depend on the results of the other two matches: Wales go to Italy, and England, the other contender, close the tournament at home to France.

England lead with a points difference of plus 37, Ireland have plus 33, and Wales plus 12.

Ireland captain Paul O’Connell, playing his 100th match for his country, eschewed penalty kicks at goal for attacking lineouts four times, and came away with a try only once.

That cut Wales’ lead to 20-16 with 11 minutes to go.

Wales fullback Leigh Halfpenny kicked over his fifth penalty with five minutes left to force Ireland to play for a barely consoling draw.

In the last frenzied minutes of a pulsating match, Ireland couldn’t get over in the left corner from two lineouts. When time was blown, Wales erupted in unabashed joy, having won three in a row to go to Rome next week still with a shot at a third title in four years.

“It’s the most I’ve been exhausted in a Test match,” Sam Warburton said after his Welsh record 34th Test as captain. “The attitude and the effort of the guys was second to none. It was absolutely unbelievable.

“This was as satisfying as the win against South Africa in the autumn. Ireland are that good.”

Ireland lost not only a precious Grand Slam chance, but also lost for the first time in 11 matches and 13 months. They have a week to rebound from the deep disappointment of not knocking out Wales.

“We probably lost the battle in the air, and we didn’t quite get the speed of ruck ball that would have helped us, but we didn’t help ourselves,” Ireland coach Joe Schmidt said. “A lot of credit has to go to the Welsh defense. They made a lot of tackles, and they hung in really well when we did get pressure inside their 22.”

Wales made a staggering 289 tackles, missing 22. Ireland made 104. Lock Luke Charteris led the tackle count with 37, then Warburton with 30.

For at least eight minutes in the third quarter, Ireland laid siege in the Wales 22. But Wales repelled ruck after ruck to the point where Ireland were ultimately pushed outside the 22. When Ireland received a penalty, Wales defense coach Shaun Edwards screamed and jumped in anger.

But Ireland, again, didn’t want three points. A rolling maul off a lineout made 10 meters, and when the ball was spat out, winger Tommy Bowe was cut down by Jamie Roberts, and fellow wing Simon Zebo was sent flying back by George North. When Wales received a penalty and cleared, their fans cheered as if they’d scored the match-winning try.

Ireland couldn’t score a try, but Wales could.

Jonathan Davies surged into the Irish 22. His midfield partner Roberts, who’d knocked heads with Ireland hooker Rory Best, was subbed off for Scott Williams, who scored the try out of nothing two minutes later. Ireland defenders hung off, and Williams ran through a huge gap between No. 8 Jamie Healsip and Bowe. That made it 20-9 without the conversion, and a quarter to go.