Shaw brings positives and negatives to Lions says Matfield

England's Simon Shaw (L) is tackled by South Africa's Francois Steyn (R) and Schalk Burger in the Rugby World Cup final at the Stade de France Stadium in Saint-Denis, near Paris, October 20, 2007.

JOHANNESBURG (Reuters) - South Africa vice-captain Victor Matfield said on Friday the selection of Simon Shaw at lock for the British and Irish Lions would add physical presence but detract from the team's mobility.

Englishman Shaw, 36, will make his Lions test debut on his third tour in the second test against the Springboks in Pretoria on Saturday (2 p.m. British time) as one of three changes to the pack.

He replaces Wales's Alun-Wyn Jones in an eight who were outmuscled in the rucks and mauls during the 26-21 first test defeat with lock Matfield dominating the lineouts.

"We saw at the last World Cup that Simon Shaw is very good at disrupting the rolling mauls and I think that's why they have brought him in, to get stuck in when we try to drive the ball," Matfield told a news conference.

"He's also 2.03 metres tall so he's not a bad option for the lineouts either. But when you win something in one area, sometimes you lose something else in another area. Alun is very quick around the ground and he hits a lot of rucks, so I'll be interested to see if it makes a difference to the Lions not having him."

Matfield captained the Bulls, who have been unbeaten in 11 matches at Loftus Versfeld, in their triumphant Super 14 campaign. He said the venue and altitude would not be determining factors.

"Loftus won't win a test for you, but if we can put the Lions under pressure then hopefully the crazy crowd and the altitude can take effect. But for the last few years, Ellis Park has been much better for the Boks, we've actually lost a few games at Loftus," he said.

Matfield said the return of flanker Schalk Burger would help the Springboks maintain their supremacy in the rucks, even though the former world player of the year is replacing a specialist fetcher in Heinrich Brussow.

"Schalk has a lot of experience and he's a big, strong ball-carrier who gets all around the park. He's a bit bigger than Heinrich and, although he's not as renowned as him for being a fetcher, Schalk is still very strong over the ball in the rucks.

"The Lions will need to put a pair of players on him to stop him ripping the ball away. The more numbers they have to commit to the rucks to keep Schalk out, the easier it will be for us to defend."

(Editing by John Mehaffey)