Ronan O'Gara regained his kicking form to fire Munster to an opening 28-23 Heineken Cup victory over Castres at Thomond Park, Limerick.

The Lions fly-half was badly off target at Murrayfield last weekend when Ireland folded against Scotland. But he put that behind him to turn in a brilliant display with the boot to keep a French side containing Scotland's Gregor Townsend at bay.

O'Gara sent over six penalties and a drop goal and converted Jason Holland's first-half try to give Munster a hard-won victory.

It was a tight contest throughout with referee Chris White the most prominent figure in the early stages.

When White took Munster prop Martin Cahill to task for twice dropping the scrum after three minutes Castres Romain Teulec sent over a penalty 45 metres out from straight in front of the posts to put the French side on the scoreboard.

The Irishmen were back on level terms in the 11th minute when Castres flanker Arnaud Costes came in from the side at a ruck in front of the post and conceded the simplest of penalties for O'Gara, earning himself a yellow card in the process.

Munster failed to take advantage of their numerical superiority with Teulec adding two more penalties in Costes' absence. Things got worse for Munster when O'Gara missed a 24th minute penalty attempt - his only blot on the afternoon - but a minute later the pressure was eased when Holland broke through the Castres defence with an angled run to touch down and O'Gara edged 10-9 in front with the conversion.

Castres hit back on the half hour moving the ball through quick hands to put in full-back Ugo Mola for a try in the corner. Teulec missed the conversion but the French went in at the break 14-10 in front.

The nip and tuck continued at the restart. O'Gara knocked over two penalties in the first seven minutes of the half as Castres Romain Froment was sin-binned by a flagrant breach of the offside laws. Then Teulec and O'Gara exchanged two penalties apiece and Munster were 22-20 ahead at the hour mark.

It set up a rousing finale as the Thomond Park crowd raised the temperature.

It certainly inspired Munster and rattled the French visitors.

O'Gara popped over a drop goal from the 22 and Castres decision to take a quick restart backfired when Stringer popped the ball back up field over the French defence and forced full-back Mola to panic in the dead ball zone.

O'Gara then took another easy penalty as Castres strayed offside and Munster had an eight-point lead.

Teulec scraped back an 80th minute penalty but the Irish side were home and dry.