The Welsh region may have won seven from seven so far in the GUINNESS PRO12 but Ulster are not far off the pace, back in third with just one league defeat - at Zebre.

This is Ulster's fourth successive GUINNESS PRO12 game at the Kingspan Stadium, a venue where they have been defeated only once in the competition since September 2013.

They have also won four of their last five encounters with Ospreys, although in all five instances the losing side achieved a bonus point.

Neil Doak has the luxury of selecting three players released from international duty this week, with Darren Cave, Craig Gilroy and Stuart Olding each taking their place in the starting line-up.

Paul Marshall and Paddy Jackson continue their partnership in the half-backs, while Roger Wilson has recovered from a shoulder injury to start an No.8 in an unchanged pack from victory over Newport Gwent Dragons in round seven.

South African van der Merwe takes his place in that pack - alongside Lewis Stevenson at second row - and he is excited to welcome the league leaders to Belfast.

"I've never played them before but they are top of the log and haven't lost a game so that speaks for itself," he said. "But it's home advantage and the Kingspan gets fired up for Friday night games.

"This is a big ten weeks and there are some very important PRO12 and European games coming up."

Ospreys boss Steve Tandy will have to do without as many as ten internationals, making five personnel changes to the team that beat Connacht last time out.

Ashley Beck and Aisea Natoga come into the back line, with Tom Grabham switching over to the left wing, while Martin Roberts and Sam Davies continue their half-back partnership.

Dmitri Arhip comes into the front row to join Duncan Jones and Sam Parry and Lloyd Peers captains the Ospreys from the second row.

And Sam Lewis is the only survivor in the back row, as Dan Baker and James King return to the side, while Rory Thornton and Ifereimi Boladau will make their GUINNESS PRO12 debuts if they come off the bench.

Ospreys have already equalled their best-ever start to a PRO12 season - set a decade ago - and have the chance to go one better at the Kingspan Stadium.

They have won their last four games against Irish provinces, since Munster were victorious at Liberty Stadium in February, but have won in Belfast just once in their last four visits.

"There's no doubt about it, the next two weeks are going to be a real challenge for this group but like any Ospreys team, they won't shirk it and will give everything," said Tandy.

"It's a crucial period of the season, one that we didn't do well in last season, and we all know how important a good result or two during the international period can become the end of the year.

"These boys have to take responsibility for what we are trying to achieve, and have to realise that this is a fantastic opportunity for them to really make a positive impression in the shirt.

"We've got some big games coming up, this is the start of a massive period of rugby running through to the end of January, and everyone in the squad will have a part to play if we are going to achieve our aims.

"It's important that our preparation is spot on and that everybody involved knows their roles and responsibilities, you can't go to places like Ulster and Leinster if you aren't 100 per cent."

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At Kingspan Stadium, 7.35pm.
Live on BBC NI
Referee: Neil Hennessy (WRU, 21st competition game)
Assistant Referees: Nigel Correll, Brian MacNeice (both IRFU)
Citing Commissioner: John Cole (IRFU)
TMO: Kevin Beggs (IRFU)