Ronan O'Gara kicked Munster back to the top of the Magners League last night as they triumphed over the reigning champions at Thomond Park.

A 37th-minute penalty from replacement O'Gara was the sole score of a forgettable first half, but the second period burst into life as Doug Howlett and Tommy Bowe swapped tries.

O'Gara's right boot dominated the remainder as he added four penalty goals for a 17-point personal haul, making Richard Fussell's late try a mere consolation for the off-colour Ospreys.

There was plenty of added interest in this early season tussle, with Munster favourite Alan Quinlan winning his 200th provincial cap and the sides set to lock horns in the Heineken Cup in December.

Having already lost Denis Leamy to a rib injury prior to the match, Munster had to tweak their line-up early on when winger Ian Dowling's night was ended by a hip problem. O'Gara was brought in at out-half, with Paul Warwick moving to full-back.

Both Warwick and O'Gara missed kickable penalties in the opening 10 minutes and although Munster bossed play in the first quarter, the Ospreys were able to soak up the pressure.

A kick chase from Johne Murphy got Munster to within sight of the try-line, and Ospreys full- back Lee Byrne was fortunate to avoid a yellow card for hands in the ruck as Tomas O'Leary prepared to pass.

Sam Tuitupou was a productive ball carrier in Munster's midfield, but any space was quickly closed down by the visitors. A hack downfield from Byrne was well chased by Shane Williams who gave Warwick no time on the ball.

The mistakes continued from both sides, most notably at lineout time and in contact. An ankle injury forced Ian Evans off, after he fell awkwardly in a lineout, and Howlett, Munster's captain for the night, lacked support as he jinked his way into scoring range.

O'Gara watched a long-range penalty effort fail to clear the crossbar, on the half hour, but he sent Munster into a 3-0 lead shortly before half-time, punishing the Ospreys for a scrum infringement.

Munster continued to force the issue in the second half, declining a shot at the posts before momentum from a scrum led to Warwick sending a skip pass out for Howlett to glide in at the corner. O'Gara struck a superb conversion for 10-0.

The Ospreys hit back in the 45th minute when Williams' deft pass invited Bowe into space over halfway and the Ireland winger had the pace to outstrip Warwick for the left corner, with Biggar missing the conversion.

Bowe was back on the defensive to thwart Felix Jones soon after, and Munster, holding the edge up front, began to turn pressure into points. With the Ospreys losing Marty Holah to the sin-bin for repeated ruck offences, O'Gara kicked four successive penalties - two of them while the visitors were down to 14 men.

With 10 minutes to go, the Munster forwards had laid the platform for victory at 22-5. The Ospreys opened up in the closing minutes, and Andrew Bishop almost made it over for a try.

Bishop was brought down close to the posts, and Munster's Billy Holland was duly yellow carded for not rolling away.

After a series of scrums, Biggar scooped a long pass out to the right for replacement winger Fussell to score, but it was too little, too late as Munster sealed the points.

Munster F Jones; D Howlett, J Murphy, S Tuitupou, I Dowling; P Warwick, T O'Leary; M Horan, D Fogarty, J Hayes, D O'Callaghan, D Ryan, A Quinlan, N Ronan, J Coughlan Subs R O'Gara for Dowling, 4 mins; D Varley for Fogarty, 29 mins; T Buckley for Hayes, 40 mins; W du Preez for Horan, 50 mins; B Holland for Quinlan, 69; P O'Mahony for Coughlan, 69 mins; D Barnes for Jones, 74 mins; P Stringer for O'Leary, 78 mins

Ospreys: L Byrne; N Walker, T Bowe, A Bishop, S Williams; D Biggar, J Nutbrown; P James, M Davies, C Mitchell, A Wyn Jones, I Evans, J Collins, M Holah, J Thomas.
Subs Ian Gough, for Evans 33 mins; R Hibbard for M Davies, 48 mins; A Jones for Mitchell, 48 mins; R Webb, for Nuttbrown 58 mins; D Jones for James, 60 mins; B Lewis for Holah, 67 mins; G Owen for Byrne, 67 mins; R Fussell for Walker, 67 mins