London - England has an Ashes series looming ahead of it and South Africa a lingering history of one-day failures behind it.Both will try and convert those distractions into motivation for Wednesday's first Champions Trophy semi-final at the Oval.There's no doubt that in the scheme of England's busy summer, the Champions Trophy is a distant second in importance to the clash with fierce rival Australia and defending the Ashes.The South Africans, meanwhile, could be overrun by their desperation to finally do well at a major limited-overs event and end coach Gary Kirsten's tenure on a high.Rather than a hindrance, Alastair Cook and his England team would undoubtedly see a place in the final in the last ever Champions Trophy as ideal build-up for Australia, even if they've already struck the first blow by beating the Aussies at this tournament.Adding a first ODI title on home soil would put England in just the right mood to host the Ashes."It's such an exciting place for a player to be," England captain Cook said on Tuesday of England's progress to the last four. "We have almost played knockout cricket throughout this Champions Trophy and we have come here to try and win the tournament. We have got an amazing opportunity to try and do that."A given in knockout games, England-South Africa will be decided by "whichever side handles the pressure," Cook said.Both teams have a fairly poor record of doing that in big ODI games.England has lost three World Cup finals and also fell in the 2004 Champions League decider. South Africa's late flops in one-day tournaments have become legendary since winning the first Champions Trophy in 1996.The Proteas now hear the term "chokers" at every ODI tournament and it means the team regularly plays down its expectations.Left-arm seamer Lonwabo Tsotsobe said this week that South Africa was "minding its own business" ahead of the England semi."We know it's a semi-final and it's the big stage, but the boys are still in the same mindset that they had during the group matches," Tsotsobe said. "Every match there was a big game so nothing has changed."Along with the Ashes, other outside influences have threatened to affect England's campaign: a late-night bar incident involving Australia's David Warner and England's Joe Root and accusations of ball tampering by former England captain and current television commentator Bob Willis."It's another day ... It's another game," Cook said, shrugging off those off-field issues. "What's gone on in the past has gone on. It has no relevance (to the semi-final)."South Africa skipper AB de Villiers gave England the benefit of the doubt when it came to the tampering allegations."If they are doing something with the ball then it is definitely a concern, yes," De Villiers said. "But we've got no proof of that."It's also uncertain if key bowlers Graeme Swann and Dale Steyn will turn out for their countries in the semi-final. Swann has calf and back problems, and Steyn has struggled with a side injury.Cook said off-spinner Swann wouldn't be risked against South Africa if he's not 100 percent fit with the Ashes still to come and England finding an able slow-bowling replacement in James Tredwell."Tredders (Tredwell) is an exceptional bowler so we might be cautious with him (Swann) and be sensible," Cook said.Conversely, South Africa may be prepared to take the gamble on spearhead Steyn with the Champions Trophy a season-ender for the Proteas."It will be nice to have him in the team again tomorrow," De Villiers said. "It looks like we've got a good chance. I hope we can have him on the park ... but we definitely can beat England without him."