Champions Trophy: England will not take Graeme Swann risk

England will not risk Graeme Swann's long-term fitness despite facing a Champions Trophy semi-final against South Africa at The Oval on Wednesday.

The off-spinner, 34, has only played in one of England's three group matches because of back and calf injuries.

"We have not trained yet so we will see how he pulls up in training," England captain Alastair Cook told BBC Sport.

"We will not be taking too many risks on him, just for the luxury we have with James Tredwell in our squad."

A calf problem ruled Nottinghamshire's Swann out of Sunday's crucial 10-run victory against New Zealand, after he had already missed the opening 48-run win over Australia with a back spasm.

With the start of the Ashes series against Australia less than a month away, England have chosen to be selective about when they field their leading spinner, who took 14 wickets in the last home Ashes series in 2009.

In his absence, Kent skipper Tredwell has played a steadying role in the current competition, taking one wicket for 78 runs in 14 overs across his two appearances.

Tredwell has played in 17 one-day internationals since his debut in 2010, primarily as a stand-in when fellow off-spinner Swann has been rested.

"He [Tredwell] has been doing a great job in the one-day game for us," Cook added. "We are very lucky, but have to be careful with Swann."

England made it to the semi-finals when they defied Sunday's rain and a late New Zealand rally to secure a narrow win.

Cook believed the tension in Cardiff provided good practice for Wednesday's game against the Proteas.

"I will go back to Cardiff, which was effectively a quarter-final for us," he said. "You do feel the pressure is more heightened, as it is another must-win game.

"It is a really exciting place to play, playing on that edge. Hopefully, we can deliver under that pressure."

England's Champions Trophy campaign has featured allegations of ball tampering made by former captain Bob Willis following the seven-wicket defeat by Sri Lanka, an accusation which England limited-overs coach Ashley Giles denied.

South Africa captain AB de Villiers admitted he was worried about the claims ahead of the meeting at The Oval.

"If they are doing something funny with the ball it's definitely a concern, yes, but we've got no proof of that," said the 29-year-old Proteas skipper.

"They seem to get it to reverse quicker than the other teams but maybe they've just got really good skills. All teams try to get it and we haven't managed to succeed as yet.

"We will try it again tomorrow to see if we can reverse the ball. It's probably something the ICC [International Cricket Council] and umpires will look at but it's not really up to me to comment on it."

England (from): Alastair Cook (capt), Ian Bell, Jonathan Trott, Joe Root, Eoin Morgan, Jos Buttler (wkt), Ravi Bopara, Stuart Broad, James Tredwell, Graeme Swann, James Anderson, Steven Finn.

South Africa (from): Colin Ingram, Hashim Amla AB de Villiers (capt/wkt), JP Duminy, Faf de Plessis, David Miller, Ryan McLaren, Robin Peterson, Chris Morris, Dale Steyn, Lonwabo Tsotsobe, Rory Kleinveldt, Aaron Phangiso.

Umpires: K Dharmasena (SL) and R Tucker (Aus)

Third umpire: B Oxenford (Aus)

Match referee: J Srinath (Ind)