Cape Town - Springbok coach Rassie Erasmus has hailed the impact of substitute loose forward Francois Louw in his side's Rugby World Cup semi-final win over Wales on Sunday.

READ: ROB HOUWING'S SPRINGBOK PLAYER RATINGS

In the tightest of contests, Wales had levelled the scores at 16-16 going into the final 10 minutes before a trademark Louw turnover won the Boks a turnover on the ground won the Boks a penalty in the 74th minute. 

Flyhalf Handre pollard slotted the goal and the Boks went on to secure a 19-16 win and a place in the final where they will take on England on Saturday. 

Erasmus was asked after the match just how important that moment from Louw was. 

"It was massive," the coach said at his press conference.

"There were a few contributions from guys that came off the bench that made massive differences. Frans Steyn put a grubber through that got them stuck back into their 22.

"Francois Louw gave a penalty away when he just came on to the field, and I thought, 'Hell, OK, maybe that was the wrong call that I put him on'. Then two minutes later, he got the vital turnover inside our 22. Sometimes things work out for you, and sometimes they don't.

"A guy like S'bu (Nkosi) got a chance today. There were times in the game where he got found out, but there were certainly times when we had wonderful opportunities, and he played really well.

"That specific turnover by Flo (Louw) was very important for us to go through to the final."

Saturday's final will also be played in Yokohama and kick-off is at 11:00 (SA time).