London, Aug 16 : South Africa cricket team chief coach Mark Boucher has said the key to defeating England in their backyard is to "stop their momentum" and "maybe change it". South Africa and England will be involved in a three-Test series, with the opening match scheduled to be played at Lord's from August 17. Momentum is on the hosts' side as they have won four back-to-back Tests including the three games against New Zealand and the rescheduled fifth Test against India, where the Ben Stokes-led side chased down a record total to win by seven wickets. On the eve of the opening Test, Mark Boucher decided to hold his cards close to his chest when asked about how his side would try and combat their opponents at Lord's. "I don't know, I'll tell you on the day," Boucher was quoted as saying by ICC. "We've got to be adaptable in Test cricket. It's just about finding a way to try and stop their momentum and maybe change it." South Africa have lost just two Test matches during the current World Test Championship (WTC) period and Boucher wants his team to carry that momentum through to the series against England. "We believe we've been playing a nice brand of cricket and played some tight series recently where we have come out on top," he said. "We want to be smart, play aggressive cricket but you've got to be smart with that as well. "The bottom line is this game is between bat and ball and we've got to make smart decisions at certain times of the game, and we are focused on trying to do that. England will probably do the same, they have their brand they want to play. We've just got to try and match it on the day and try find ways to negate it." South Africa are currently leading the World Test Championship table and are in pole position to clinch a WTC final berth. Australia are a close second in the race to secure a berth for the WTC final in 2023. South Africa are hopeful their pace spearhead Kagiso Rabada is able to overcome his ankle concern and feature in the opening Test, while fellow quick Duanne Olivier will miss the entire series with a hip injury. /IANS