Leinster were in danger of suffering their first home Magners League defeat since September 2008 before taking a stranglehold in the second half and running out 20-16 winners over the Ospreys.

This top of the table clash fizzed along in the opening half with the Ospreys very much to the fore. An impressive display from out-half Dan Biggar, who converted his own try and kicked three penalties, had the visitors 16-10 ahead at half-time.

But Leinster’s canny knack of finishing on top in tight games helped them edge ahead in the second period, with centre Fergus McFadden converting Shaun Berne’s try and grabbing the insurance points from a late penalty.

Both sides were much changed from their last outings and there were also late changes as scrum half Paul O’Donohoe came into the Leinster team and Gareth Owen replaced Lee Byrne at full-back for the Ospreys.

The visitors managed to dominate the first half in terms of possession and territory, with a decidedly flat Leinster side making only two visits to the Welsh region’s 22.

Still, Leinster opened the scoring against the run of play in the twelfth minute. Back rowers Filo Tiatia and Jerry Collins linked in midfield as the Ospreys rumbled into the home 22.

But, off the ensuing ruck, Biggar’s looping pass was too ambitious, Isa Nacewa plucked it out of the air and the Auckland-born winger had the pace to run over unopposed from 80 metres out.

McFadden tapped over the conversion but discipline and restarts – two areas Michael Cheika singled out for additional work after last weekend’s Heineken Cup quarter-final win – let the hosts down again.

The Ospreys attacked with vigour off the restart, and Biggar traded penalties with McFadden before the men in white bossed the remainder of the opening half.

The talented number 10 hit a monster penalty from just inside the Leinster half to close the gap to 10-6 and Shane Williams was bundled into touch in the right corner as the Ospreys continued to press out wide.

They adjusted coming up to half-time, finding more space through the middle of the Leinster defence. Biggar, having missed an earlier drop goal, redeemed himself by waltzing through for a 31st minute try, shrugging off Mike Ross’ challenge after the Ospreys had profited from an Ian Gough lineout steal.

Full-back Owen produced a solid tackle on Nacewa to win turnover ball and an eventual penalty which Biggar dispatched through the uprights with aplomb.

Gordon D’Arcy and Jamie Heaslip tried to inject some pace into Leinster’s attacks coming up to half-time, but the Ospreys stood firm for a 16-10 half-time lead.

However, it was a different story after the break as Leinster took the intensity up a notch or two and the Ospreys’ effort waned, which was understandable in this their third game in six days.

Replacement James Hook, the two-try hero against Ulster, could not exert the same influence on proceedings and Australian Berne saw more ball behind an advancing Leinster pack.

McFadden missed an early penalty chance, but out-half Berne settled the league leaders’ nerves by breaking the first line of defence, off quick lineout ball, to canter in under the posts on a diagonal run. McFadden converted for a 17-16 lead.

There was a long listless period before McFadden missed the target from a 66th minute penalty and Berne also had a drop goal ruled out by the match officials. But, despite ending the game on the defensive, Leinster had sealed the points with five minutes to go.

Their grip on the game was tightened when Ospreys lock Gough was sin-binned for blocking Berne in midfield as he chased his own chip.

McFadden pulled out all the stops to nail his most difficult kick of the night, driving Leinster to their 14th straight league win at the RDS and putting them within touching distance of the semi-finals.

Speaking after the game, Ryan Jones, who came on as a second half replacement, remained positive about the Ospreys’ chances of making the play-offs. They are now seven points behind Leinster in the table.

"We’ve come away to Ireland for a week after the disappointment of a loss in Europe last weekend and we’ve got six points from two very tough away fixtures," said Jones.

"We’re disappointed with the second half today, but all in all, I think it’s been a very good trip and experience for us.

"It’s three games in six days and that’s tough at this level. The pitches have been dry, the games have been fast, there’s been a lot of phases, it’s been physical and an emotional rollercoaster that we’ve been on."

He added: "We’re confident that we can beat anyone on the day. We showed some maturity, there were some guys who haven’t played for a long time who put in some fantastic performances today, like Ed Shervington and Gareth Owen, they are the guys who are the future.

"But, we’ve got some big fixtures left this year, we’ll try and get some more points to get us into the play-offs. We know that we are capable of it on the day."

Giving his take on the game, Leinster coach Michael Cheika said: "I didn’t have to say too much to the boys after the game. In the first half we were average at best. The Ospreys are a very good side and we know that we were probably lucky to be only six points behind at the break.

"They played with a big hard defence (against us) and I’d say that we could see them (the Ospreys) again before the end of the season with the way things are shaping up.

"We rested a couple of players tonight and could have a few more players to maybe come back next week. We’ll just wait and see."