Rugby World Cup 2011: Jamie Roberts highlights Seilala Mapusua threat
Last updated on .From the section Rugby Union

Jamie Roberts is determined to keep a tight rein on rival centre Seilala Mapusua when Wales meet Samoa in their World Cup Pool D game on Sunday.
The British and Irish Lions star, 24, says Samoa captain Mapusua was one of the players he held in high regard as he developed his own game.
"They've got quality players, Mapusua is one of them," Roberts said ahead of their clash in Hamilton.
"He's certainly a centre I've admired growing up and learning my trade."
Mapusua, 31, played with distinction for London Irish over the past five seasons, but will join his new team, Japanese side Kubota Spears, after the World Cup.
"As a player he's done very well for London Irish over the last couple of years and he's certainly a player we need to watch out for," Roberts said.
Wales' 17-16 defeat in their opening game against South Africa last weekend means realistically they cannot afford to lose another game in Pool D if they want to qualify for the quarter-finals.
Samoa showed their talent when they began their campaign on Wednesday with a 49-12 win over group minnows Namibia, and have beaten Wales in both their previous World Cup encounters in 1991 and 1999.
"Obviously [Alesana] Tuilagi showed his quality in their first game against Namibia, in opposition 22s he's certainly a very dangerous player and he scores tries for fun," Roberts added.
"[Sailosi] Tagicakibau and the Pisi brothers [George and Tusi] as well are a huge threat, so defensively more than anything we need to be on the money this week.
"It's a huge game for us defensively and we can't afford any lapses in concentration as maybe we did last weekend, and that cost us in the end last week.
"We all know what Samoa are going to bring, they're a very physical team with ball in hand and physical in defence.
"Certainly they have some players who can create things out of nothing and defensively that's very hard to prepare for.
"But it's all about saving our emotion now and making sure that mentally we're right for that 80 minutes come Sunday."
Samoa are optimistic that Tusi Pisi will be fully fit to face Wales at the Waikato Stadium, after the fly-half playmaker limped off nursing a hamstring injury against Namibia.
Samoa coach Titimaea Tafua has named Pisi to start despite the doubts over the niggle afflicting the Suntory Sungoliath player.
"He [Pisi] is 80%, and he might be 99% by tomorrow [Friday] and we still then have a whole other day before the match," Tafua said.
The starting line-up shows just one change from the Namibia game with flanker Ofisa Trevaranius replacing Taiasina Tuifua, who still features on the bench despite suffering a rib injury.
Wales: James Hook (Perpignan); George North (Scarlets), Jonathan Davies (Scarlets), Jamie Roberts (Cardiff Blues), Shane Williams (Ospreys); Rhys Priestland (Scarlets), Mike Phillips (Bayonne); Paul James, Huw Bennett, Adam Jones (all Ospreys), Luke Charteris (Newport Gwent Dragons), Alun Wyn Jones (Ospreys), Dan Lydiate (Dragons), Sam Warburton (Blues, capt), Toby Faletau (Dragons).
Replacements: Lloyd Burns (Dragons), Gethin Jenkins, Bradley Davies (both Blues), Andy Powell (Sale Sharks), Tavis Knoyle, Scott Williams (both Scarlets), Leigh Halfpenny (Blues).
Samoa: Paul Williams; Sailosi Tagicakibau, George Pisi, Seilala Mapusua, Alesana Tuilagi; Tusi Pisi, Kahn Fotuali'i; Sakaria Taulafo, Mahonri Schwalger (capt), Anthony Perenise, Daniel Leo, Kane Thompson, Ofisa Treviranus, Maurie Faasavalu, George Stowers.
Replacements: Ti'i Paulo, Census Johnston, Joe Tekori, Manaia Salavea, Jeremy Sua, Eliota Sapolu Fuimaono, Tasesa Lavea.