England coach Chris Silverwood hopes Jos Buttler's return to form in the Twenty20 series decider against South Africa will help revive his test career in next month's tour of Sri Lanka. The wicketkeeper-batsman's blistering knock of 57 runs off 29 balls helped England secure a five-wicket win and a 2-1 series triumph on Sunday. Buttler has struggled in the longest format, however, managing just 158 runs in his last five tests against South Africa and New Zealand. 'Runs breed confidence within a batsman -- to see him come off with a smile on his face in the way he did was superb,' Silverwood told British media. 'Hopefully he'll take a lot of confidence from it and bring that with him to Sri Lanka.' Silverwood said England were close to finding the right balance in the squad ahead of the T20 World Cup in Australia later this year. 'The more they've played together, the better they've got -- we've seen the improvement throughout the series so I don't think we're a million miles away,' Silverwood added. 'But we'll obviously refocus now on the test series against Sri Lanka and look to pick up where we left off here.' Sri Lanka host England in Galle from March 19 to 23 and Colombo from March 27 to 31.