United Rugby Championship league leaders Leinster kept their unbeaten record going this season with a hard-fought victory over Ospreys.

Leinster responded with tries from Dan Sheehan, Hugo Keenan and Jimmy O’Brien.

It was a 14th Leinster win of the season with 12 league victories extending the advantage at the top of the table to 12 points.

The Ospreys’ defeat halted a three-match winning sequence for Toby Booth’s side who drop to 13th.

The home side battled manfully with a determined defence, marshalled by captain Justin Tipuric, scrum superiority and the ball-carrying ability of centre and player-of-the-match Keiran Williams, who would have impressed Wales coach Warren Gatland.

Ospreys eventually ran out of steam as they now trail Cardiff by five points in the battle to finish as the top Welsh region.

All four Welsh sides are in the bottom half of the table with Cardiff in the highest position of 10th.

Both Ospreys and Leinster were missing key players. Ireland captain Johnny Sexton was ruled out through injury for Leinster with some other international personnel also absent and flanker Rhys Ruddock leading the visitors in Swansea.

Wales quartet Adam Beard, Alex Cuthbert, Rhys Webb and Jac Morgan were missing with George North, Owen Watkin and Dan Lydiate already on the sidelines.

Booth made eight personnel changes from the side that defeated Cardiff with Cai Evans, Mat Protheroe, Reuben Morgan-Williams, Nicky Smith, Tomas Francis, Dewi Lake, Rhys Davies and Morgan Morris starting.

Fly-half Owen Williams was a late withdrawal with Jack Walsh starting instead, while Ospreys also lost wing Protheroe to an early arm injury.

This forced a further reshuffle with full-back Evans switching to the wing, centre Michael Collins reverting to the number 15 role and replacement Joe Hawkins coming on in midfield.

The hosts overcame this disruption with a burst from centre Williams which set up a successful penalty attempt for Evans.

A quick tap penalty from number eight Morris released scrum-half Morgan-Williams who fed wing Giles to score with Evans converting from the touchline.

Leinster responded with a Harry Byrne penalty but Ospreys’ defence initially held firm and the home side were buoyed by some scrummaging superiority.

Italian referee Andrea Piardi baffled the Swansea supporters with a couple of forward pass decisions against Ospreys and also penalised the home set-piece.

This decision set up the platform for the opening Leinster try for hooker Sheehan with Byrne converting to level the scores at half-time.

Piardi left the field at half-time to a chorus of boos with members of the Ospreys coaching staff also looking bemused at some of his first-half decisions.

Evans restored the Ospreys’ advantage with an early second-half long-range penalty with captain Tipuric inspiring his side at the breakdown.

Evans’ third penalty extended the lead to six points before Ireland full-back Keenan produced a moment of class after gliding outside the attempted tackle of replacement home hooker Scott Baldwin.

Byrne converted to give Leinster the lead for the first time with the Irish side having the luxury of bringing on world player of the year Josh Van der Flier from the replacements bench after earlier introducing Ireland lock James Ryan.

With British and Irish number eight Jack Conan starting to impress, wing O’Brien sprinted over for the third try.

Byrne’s conversion took Leinster’s advantage to eight points but Ospreys returned to within a score with Evans’ fourth penalty.

The home side looked for the match-winning score but were repelled by Leinster who gratefully held on for the victory.

Ospreys: Cai Evans; Mat Protheroe, Michael Collins, Keiran Williams, Keelan Giles; Owen Williams, Reuben Morgan-Williams; Nicky Smith, Dewi Lake, Tomas Francis, Rhys Davies, Alun Wyn Jones, Ethan Roots, Justin Tipuric (capt), Morgan Morris.

Replacements: Scott Baldwin, Gareth Thomas, Tom Botha, Huw Sutton, Harri Deaves, Matthew Aubrey, Joe Hawkins, Luke Scully.

Leinster: Hugo Keenan; Jordan Larmour, Jamie Osborne, Charlie Ngatai, Jimmy O’Brien; Harry Byrne, Cormac Foley; Cian Healy, Dan Sheehan, Michael Ala’alatoa, Ross Molony, Brian Deeny, Rhys Ruddock (capt), Scott Penny, Jack Conan.

Replacements: John McKee, Michael Milne, Vakhtang Abdaladze, James Ryan, Josh van der Flier, Nick McCarthy, Ross Byrne, Rob Russell.

Referee: Andrea Piardi (FIR)

Assistant referees: Dewi Phillips (WRU), Jason Bessant (WRU)

TMO: Matteo Liperini (FIR)