RUGBY Munster v N-S Ospreys, Thomond Park, 5.15: So here we go again. If it's a Saturday afternoon in January, it must be another grudge match in Thomond Park, with Munster again putting their winning run (now at 20) on the line at their Limerick citadel in another crunch, must-win game against visitors who travel over with a cocky spring in their step. You could never tire of it.

The Ospreys' relatively upbeat mood will have been further buoyed by the news that in addition to Ronan O'Gara, Rob Henderson has been pronounced hors de combat. Although cleared of concussion by a neurologist, and an initial X-ray showed no damage from the knee in the head Henderson sustained against Leinster last week, a further scan yesterday revealed he had suffered a non-displaced fracture in his cheekbone.

"Hendo was keen to play but it could do serious damage to him if he got another whack to the same side of his face, so we decided it was better not to risk him," confirmed coach Alan Gaffney. Hence, Mike Mullins moves to inside centre, with the ripple effect seeing Shaun Payne moving in to outside centre, Mossy Lawlor on to the wing, and James Storey called up to the bench.

It's an unfortunate blow, as the in-form Henderson's ability to set up go-forward ruck ball in the middle of the park would have been a useful weapon on what is liable to be a relatively inclement day. "Cold, windy and showery," is the local weather forecast. Well, there's a surprise.

The absence of O'Gara will already have unnerved Munster supporters all week. Even at 27, he has become something of a European Cup legend, scoring a competition record 649 points in his 50 appearances. But it's not just his goal-kicking, it's his presence, tactical kicking and ability to spark their quick tempo surges which have become the fulcrum of Munster's game. He has been an ever-present throughout a run of 46 European Cup games in a row, dating back to the quarter-final defeat against Colomiers in the 1998-'99 season.

"To think he is targeted nearly every week, it shows you how resilient he is," observed Gaffney. Nonetheless, to have a wily 31-year-old, with a dozen years in the front line of the game and 13 caps to his name, makes Paul Burke about as comforting a replacement as Munster could hope for. "Burkey's been around the block and he can handle this sort of thing," added Gaffney.

The Ospreys probably won't be as rattled by the occasion as, say, Castres were, and they are easily the best all-round team in Wales, with Duncan Jones a helluva good loosehead, a good lineout (and better defensively than Castres), a hugely accomplished scrumhalf in Jason Spice and undoubted match-winners in the prolific Gavin Henson and the twinkle-toed Shane Williams.

"There's been a bit of baggage between the sides but I don't deny that they are a mighty fine side," admitted Gaffney. "It's going to be a tough day at the office. I think a lot of people just think we have to turn up at Thomond Park, but that's a load of rubbish."

There's no doubt, too, that the Ospreys' relative familiarity with Munster is probably a help rather than a hindrance, although you know what they say about familiarity, and certainly there is bad blood from the first European Cup meeting which didn't abate in the fall-out from Munster's Celtic League win at Musgrave Park before Christmas, when Ryan Jones was sent-off for stamping and the Ospreys threw a few post-match barbs towards Peter Stringer.

Afterwards coach Lynn Jones said: "They are not infallible. They are not God's gift to rugby, they're just human beings like everybody else and they get things wrong if you apply a bit of pressure. Munster have had a good run in Europe and I'm sure they're desperate to do it this year but it's all to play for."

It was a typical throwaway remark by the engagingly candid Jones, but it will merely have served to get Munster's dander up once again, and that of another partisan full house.

This will be the sides' fourth meeting this season and their sixth in two seasons, the Ospreys winning the first three and Munster the last two. However, none of those have been here in the European Cup. Although Munster's recent brace of wins were cussedly close, the first was in the Gnoll and the second was in Musgrave Park, when Munster also rested the spine of their pack, John Hayes, Paul O'Connell and Anthony Foley.

True, O'Gara and Henderson is something of an untimely double whammy. But this is usually the month when Munster hit form, and last week's encounter with Leinster, their 13th win in their last 14 games, ought to have set them up nicely .

The key will be the extent to which the Munster pack, with their spine back in situ, can gain the ascendancy and Burke and co establish field position. Both lineouts suffered in the gales of Musgrave Park last time out, but the Munster lineout maul (responsible for seven of eight tries in their last four matches) has become quite a weapon.

At full steam, it's virtually unstoppable, a bit like Munster themselves in a European Cup tie at Thomond Park. It should be high-octane stuff.

MUNSTER: C Cullen; M Lawlor, S Payne, M Mullins, A Horgan; P Burke, P Stringer; M Horan, F Sheahan, J Hayes, D O'Callaghan, P O'Connell, A Quinlan, D Leamy, A Foley (capt). Replacements: G McIlwham, J Flannery, T Hogan, J Williams, M Prendergast, J Holland, J Storey.

NEATH-SWANSEA OSPREYS: A Durston; S Terblanche, S Parker, G Henson, S Williams; M Jones, J Spice; D Jones, B Williams (capt), A Millward, B Cockbain, J Thomas, J Bater, R Pugh, R Jones. Replacements: R Hibbard, P James, A Jones, A Newman, A Lloyd, D Bishop, E Seveali'i.

Referee: Chris White (England)

PREVIOUS EUROPEAN CUP MEETINGS: (1998-99) Munster 34 Neath 10; Neath 18 Munster 18. (2004-05) Ospreys 18 Munster 20.

FORMGUIDE: Munster - 15-9 v Harlequins (h); 20-18 v Ospreys (a); 12-19 v Castres (a); 36-8 v Castres (h). Ospreys - 17-38 v Castres (a); 18-20 v Munster (h); 24-7 v Harlequins (h), 46-19 v Harlequins (a).

LEADING TRY SCORERS: Munster - Denis Leamy 2. Ospreys - Gavin Henson 2.

LEADING POINTS SCORERS: Munster - Ronan O'Gara 41. Ospreys - Gavin Henson 75.

BETTING (Paddy Powers): 1/3 Munster, 25/1 Draw, 9/4 Ospreys. Handicap odds (= Ospreys +8pts) 10/11 Munster, 20/1 Draw, 10/11 Ospreys.

FORECAST: Munster to win.