Collins (22) has joined the club to cover for injured Welsh stars Liam Williams and Scott Williams, who both went down with serious injuries when playing for Wales at the World Cup.
The deal all happened very quickly and Collins has only just arrived in Wales for a team which is coached by former Auckland coach Wayne Pivac.
The team plays in the Pro 12 league which includes sides from Wales, Ireland, Italy and Scotland.
The season has just started for the league but the Llanelli Scarlets have got off to a good start and sit top of the table.
Collins actually qualifies to play for Wales as his grandfather was Welsh and came from Llanelli.
The Taieri back does not have any residency issues as his mother was born in the United Kingdom and he has a British passport.
The former Otago Boys' High School pupil played in the midfield and also at fullback for Otago this season and has played more than 25 games for the union, having made his debut for the team straight out of high school.
He has had a bit of bad luck with injuries over the past two years, and has been in and out of the Otago team.
It was a rushed signing with Collins finishing playing for Otago in the ITM Cup championship semifinal on October 17, sitting a university exam last Thursday and flying out for Wales last Saturday.
He has signed a deal with the Welsh club until May and will then return to play for Taieri and Otago in the ITM Cup.
Meanwhile, former Otago captain Paul Grant is making every post a winner for his Nottingham club and cannot stop scoring tries.
Grant has just set a club record at Nottingham, scoring seven tries in as many games.
Grant, who turned 28 yesterday, is in his second season with the Nottingham club which plays in the English Championship, the tier below the Premiership.
Grant has been playing up a storm for Nottingham and set a record when he scored a sixth try against London Scottish in the championship.
He has previously scored tries against Doncaster, Bristol, Moseley, Bedford and London Welsh.
He was the first forward to score six tries in as many games for the club and then scored another try in the weekend against Jersey.
